Polyester Byproduct
Cyclic oligomers generated during the extrusion and spinning of polyester fibers often migrate to the fiber surface during high-temperature wet processing. These molecules, known as matrix trimers, are crystalline byproducts that represent the most common type of oligomer found in polyethylene terephthalate textiles. This substance causes processing issues during dyeing and can ruin the appearance of finished fabrics if not properly managed.
Formation Mechanism
The high temperatures and pressure used in jet dyeing machines cause these low-molecular-weight polymers to dissolve from the interior of the polyester fiber into the dye liquor. As the dye bath cools down at the end of the cycle, the solubility of these matrix trimers drops rapidly, causing them to precipitate onto the fabric surface as fine, white crystalline deposits. These crystals can also accumulate on the internal surfaces of the dyeing equipment, clogging nozzles and pumps.
Dyeing Complication
The presence of these surface deposits reduces the brilliance of dyed shades and causes friction during subsequent spinning or sewing operations.
Removal Strategy
Dyehouses prevent the deposition of these oligomers by using high-temperature drain methods or by adding specialized dispersion agents and oligomer binders to the dye bath. These chemicals keep the matrix trimers suspended in the liquid so they can be washed away before they solidify on the fabric surface. Regular machine cleaning with caustic soda and hydrosulfite is also required to remove accumulated deposits from the dye vat walls.
This preventative maintenance avoids quality defects and ensures consistent dye uniformities across different production batches.
