How does heat setting shape the performance and quality of polyester DTY yarn? ​

In the production process of polyester DTY yarn, heat setting is a key process that determines the final performance and quality of the product. Polyester DTY yarn is polyester stretched and deformed yarn. After raw material processing, extrusion spinning, cooling and stretching, its internal structure is in an unstable state and there are residual internal stresses. Heat setting is to process the yarn by precisely controlling parameters such as temperature, time and tension to stabilize the fiber structure, thereby giving the product ideal physical and mechanical properties and dimensional stability.
​
Heat setting is carried out in special heat setting equipment. Common heating methods include hot air heating and hot plate heating. Hot air heating uses hot air as a heat transfer medium to evenly transfer heat to the yarn through circulating hot air. The advantage of this method is that the hot air can fully surround the yarn to achieve uniform heating, which can effectively avoid local overheating or insufficient heating. It is especially suitable for products with high requirements for temperature uniformity. Hot plate heating transfers heat through direct contact between the filaments and the heating plate. It has high heat conduction efficiency, fast heating speed, and can quickly reach the set temperature. It is often used in production scenarios that require rapid shaping. The two heating methods have their own advantages. In actual production, they need to be comprehensively selected based on the characteristics of polyester DTY yarn, product requirements, and equipment conditions. ​

The heat setting temperature is the core parameter in the heat setting process, which directly affects the molecular structure and performance of polyester DTY yarn. Polyester has a clear glass transition temperature and melting point. The heat setting temperature needs to be controlled in a range above the glass transition temperature but below the melting point. When the temperature is higher than the glass transition temperature, the mobility of the polyester molecular chain is enhanced, and the molecular chain that was originally oriented during the stretching process obtains enough energy to adjust and rearrange to a certain extent. At this time, by applying tension reasonably, the molecular chain can be guided to further arrange regularly to form a more stable crystalline structure, thereby improving the strength and modulus of the fiber. If the heat setting temperature is too low, the movement of the molecular chain is restricted, the internal stress cannot be fully released, the dimensional stability of the fiber is poor, and problems such as shrinkage and deformation are prone to occur during subsequent use; when the temperature is too high, close to or exceeding the melting point, the fiber will soften or even melt, resulting in structural damage, yellowing, degradation, etc., which seriously affects the product quality. Therefore, in actual production, it is necessary to accurately determine the heat setting temperature according to the specific variety, specification and product use of polyester DTY yarn through a large number of experiments and production practices to achieve the best setting effect. ​

The heat setting time also has an important influence on the performance of polyester DTY yarn. During the heat setting process, the adjustment of the molecular chain and the formation of the crystal structure require a certain amount of time to complete. If the time is too short, the molecular chain will not have time to fully rearrange and crystallize, the internal stress will not be completely eliminated, the setting effect is not good, and the elastic recovery performance and dimensional stability of the fiber are difficult to reach the ideal state; if the time is too long, it will not only cause energy waste, but also may cause fiber performance degradation, such as strength reduction, color deterioration, etc. The required heat setting time is also different under different heating methods and heat setting temperatures. Generally speaking, hot air heating requires a long heat setting time to ensure that the inside of the filament is fully heated and the molecular chain is fully adjusted due to the relatively slow heat transfer; while hot plate heating heats up quickly, and the heat setting time can be relatively shortened. During the production process, the heat setting time needs to be reasonably set according to the specific heat setting process conditions to ensure that the production efficiency is improved while ensuring product quality. ​

Tension, as an important control parameter in the heat setting process, cooperates with temperature and time to jointly affect the structure and performance of polyester DTY yarn. Applying appropriate tension during the heat setting process helps to keep the filament straight, so that the molecular chain can be better arranged along the axial direction under the action of heat, further improve the orientation and crystallinity of the fiber, and thus enhance the strength and dimensional stability of the fiber. If the tension is too large, the filament is overstretched, which may cause damage to the internal structure of the fiber and reduce the toughness and elasticity of the fiber; if the tension is too small, it cannot effectively guide the molecular chain arrangement, and the fiber is prone to relaxation and curling, which affects the appearance and performance of the product. Therefore, during the heat setting process, the tension must be precisely controlled according to the characteristics of the polyester DTY yarn and product requirements, and matched with the heat setting temperature and time to obtain products with excellent performance. ​

The heat setting process can effectively eliminate the internal stress inside the polyester DTY yarn, stabilize the fiber structure, and significantly improve the dimensional stability, elastic recovery performance, and physical and mechanical properties of the product through precise control of temperature, time, and tension. As a key link in the production process of polyester DTY yarn, a slight change in each process parameter may have a significant impact on product quality. Only by deeply understanding the principles and process points of heat setting and strictly controlling each parameter can we produce high-quality polyester DTY yarn products that meet the needs of different application fields, so that it can play an important role in many industries such as textiles, clothing, and home textiles.