Dongguan bosidi new material co.,ltd is a professional monofilament yarn supplier. PET monofilament yarn
Recyled polyester monofilament yarn
nylon monofilament yarn
The Detailed Process of Manufacturing Recycled PET Filament YarnThe transformation of a used plastic bottle into a high-quality filament yarn is a remarkable feat of modern recycling and engineering. It is a multi-stage process that emphasizes purification and consistency. Here is a more detailed look at each step:
Stage 1: Collection and Initial Sorting
Process: Post-consumer PET bottles (from curbside recycling, deposit schemes, etc.) are collected at material recovery facilities (MRFs).
Key Action: Bottles are sorted by polymer type (to separate PET from HDPE, PP, etc.) and often by color (clear, light blue, green, etc.). This initial sorting is crucial for the quality of the final product.
Output: Bales of sorted PET bottles, ready for processing.
Stage 2: Pre-Processing: From Bales to Flakes
This stage is all about deep cleaning and size reduction. The bales go through a series of machines:
De-baling & Sorting: Bales are broken open, and bottles are loosely spread out for a final manual or automated check to remove any non-PAT materials that were missed.
Grinding/Washing: Bottles are fed into a grinder where they are shredded into small, uniform pieces called "flakes." This happens simultaneously with a hot wash to remove labels, adhesives (glue), dirt, and liquid residues.
Float/Sink Tanks: Flakes are immersed in water. PET sinks, while labels (often made of PP or PE) float, allowing for easy separation.
Air Classification: Puffs of air blow away lightweight contaminants like loose label fragments.
Final Washing & Drying: The flakes undergo further washing with detergents and are then thoroughly dried in industrial dryers.
Output: Clean, dry, and consistent PET Flakes.
Stage 3: Purification and Polymerization (The Critical Step for Quality)
This stage ensures the recycled material meets the strict purity standards required for filament yarn, which is much more demanding than for, say, stuffing for pillows.
Super-Cleaning / Filtration (Melt Filtration): The clean flakes are melted. The molten PET is forced through a series of extremely fine filters (often as fine as 10-40 microns) under high pressure. This step removes any remaining microscopic solid impurities that would cause the filament to break during spinning.
Polycondensation (Optional but Common): In some advanced processes, the melted PET undergoes a process called solid-state polycondensation (SSP). This increases the intrinsic viscosity (IV) of the polymer, making it stronger and more suitable for textile applications. It also helps remove any residual volatiles or contaminants at a molecular level.
Output: High-purity, polymer-grade Recycled PET Pellets (Chips). These chips are now chemically and physically comparable to virgin PET pellets.
Stage 4: Melt Spinning into Filament Yarn
This is where the pellets are transformed into continuous yarn. The process is identical to that used for virgin polyester.
Drying: The rPET pellets must be completely dried to prevent hydrolysis (degradation by water) during melting, which would weaken the yarn.
Extrusion: The dried pellets are fed into an extruder, where they are heated to a precise temperature (around 285°C / 545°F) until they become a viscous liquid.
Metering & Filtration: The molten polymer is pumped under high pressure through a final fine filter and then through a spinneret—a metal disc with dozens of tiny holes.
Solidification (Quenching): As the thin streams of polymer exit the spinneret, they are cooled and solidified by a flow of conditioned air, forming continuous solid filaments.
Drawing/Orientation: The weak, amorphous filaments are stretched (drawn) between sets of rollers spinning at different speeds. This stretching aligns the polymer chains, significantly increasing the yarn's tensile strength, durability, and elasticity.
Texturing (Optional): To make the yarn less slick and more cotton-like, it may be textured (e.g., using air-jet texturing) to introduce loops, crimps, and bulk.
Winding: The final continuous filament yarn is wound onto bobbins or cones, ready to be used in textile manufacturing.
Summary Flowchart
Post-Consumer PET BottlesCollection & Sorting (by color/polymer)Pre-Processing: De-baling, Grinding, Washing, Label RemovalDeep Purification: Melt Filtration, PolycondensationHigh-Purity rPET Pellets (Chips)Melt Spinning: Drying → Extrusion → Spinneret → Quenching → Drawing → WindingRecycled PET Filament Yarn on ConesTextile Manufacturing (Weaving, Knitting, etc.)As your original text correctly points out, the entire process is designed to achieve a high level of cleanliness to prevent impurities from causing breaks during the high-speed spinning process and to ensure the final yarn has the consistent quality demanded by the textile industry.
