Fabric Defect
Irreversible line distortions are sharp folds or streaks that occur on the surface of synthetic textiles during wet processing. Developing polyester crease marks occurs when the fabric is subjected to rapid cooling while folded, which freezes the polymer chains in a deformed state. This aesthetic defect is difficult to remove once the line distortions are set during the high-temperature phase.
Thermal Behavior
Thermoplastic behavior dictates that synthetic fibres become highly pliable when heated above their glass transition temperature. The formation of polyester crease marks is accelerated if the fabric rope is allowed to remain in a stationary folded position inside the jet dyer at these elevated temperatures. Gradual cooling, known as controlled cooling at one degree Celsius per minute, allows the fibres to recrystallize uniformly without lock-in of these folds.
Prevention Method
Chemical lubricants and mechanical adjustments are used to keep the fabric rope moving freely during the cycle. Minimizing polyester crease marks is achieved by adding anti-creasing agents to the dye bath, which reduce the friction between the fabric folds. Ensuring high rope speed and low fabric loading also helps to continuously redistribute the creases.
Quality Assessment
Visual inspection on a lighted frame is the standard method for identifying these surface defects before finishing. Once polyester crease marks are detected, the fabric must undergo high-temperature tensionless tension framing to attempt to reset the flat structure.
