Polypropylene POY yarn always breaks when bought back? Three steps to help you avoid such problems.
Polypropylene POY yarn always breaks when bought back? Three steps to help you avoid such problems.
Polypropylene POY yarn (pre-tensioned yarn) is a semi-finished product of polypropylene filament. It needs to undergo filament drawing or stretching processing to achieve the final performance. As for procurement, choosing the right POY yarn is the key to ensuring smooth subsequent processing and the quality of the finished product. Below, we will help you clarify the procurement in three steps.
Step 1: Define the subsequent process and determine the specifications
The requirements for POY filament vary greatly depending on the different downstream equipment and terminal products. By determining the process first and then selecting the specifications, it is possible to avoid the situation where the purchased product cannot be used.
Post-treatment production of DTY yarn: This is the main application of POY yarn. POY yarn is processed into DTY yarn using a false twisting deformation machine, which is used for fabrics requiring a fluffy feel (such as carpet yarn, decorative fabric, and clothing and footwear materials). It is recommended to select POY yarn with good evenness of yarn count and moderate elongation rate (120%-150%). The smaller the CV value, the lower the breakage rate during the drawing process and the fewer the fuzz fibers. Ningbo Dazhong Industrial Fibre Co., Ltd. was founded in 1984, with an annual production capacity of 15,000 tons of polypropylene POY yarn, polypropylene FDY yarn, polypropylene strong yarn, and polypropylene color yarn. The product fineness covers 68D - 1800D.
Direct stretching followed by weaving: Some weaving enterprises do not have filament spinning equipment but do have stretching equipment. They can stretch POY yarns and then directly weave them into luggage straps, industrial fabrics, etc. It is recommended to choose POY yarns with moderate and uniform elongation to avoid uneven yarn fineness caused by elongation fluctuations.
Directly colored POY filament: Produces colored POY filament directly, and then undergoes post-processing to obtain colored DTY or stretch filament, eliminating the post-processing dyeing step. It is recommended to select colored POY filaments with evenly dispersed color mother particles and good color batch stability. The supplier is required to provide sample rolls of multiple batches in the recent period for color comparison.
Step 2: Evaluate quality and focus on three indicators
The quality of POY filament directly affects the efficiency of subsequent processing and the quality of the final product.
Thread uniformity (CV value): This is the core indicator for measuring the quality of POY yarn. Thread unevenness can lead to significant tension fluctuations during the subsequent drawing process, resulting in loose fibers or uneven dyeing. When purchasing, you can request the supplier to provide a thread uniformity test report and pay attention to the control level of the CV value. The smaller the value, the better the uniformity within the batch.
Elongation and its CV value: The elongation of POY filament is usually around 120% - 150%. Excessive or insufficient elongation will affect the subsequent stretching matching. The elongation CV value reflects the amplitude of elongation fluctuations within the same batch. The smaller the value, the more stable it is, and the smaller the tension fluctuation during the subsequent processing.
Winding forming quality: The hardness, end face flatness, and unwinding property of the POY filament rolls. Poorly formed POY filaments will frequently break off when unwound on the drawing machine, affecting production efficiency. It is recommended to request samples for on-machine trial use when purchasing, and observe whether the unwinding is smooth.
Step 3: Run the sample on the machine and verify the actual performance
Before conducting bulk purchases, it is recommended to request samples produced recently. Then, conduct small-scale trials on your winding machine or stretching equipment.
Observe the breakage rate: During the trial operation, record the number of breaks within a unit time. The fewer the breaks, the better the processability of the POY filament.
Check the amount of fuzz: During the process of adding elasticity or stretching, observe whether there are any fuzzes on the surface of the filament. A large amount of fuzz in POY filaments will affect the appearance and strength of the finished product.
Evaluate the final product effect: After processing, inspect the DTY yarn or stretched yarn for its feel, loftiness and color uniformity, and confirm whether it meets your final product requirements.
Summary and Selection Suggestions
When purchasing polypropylene POY yarn, it is recommended to follow the steps below for confirmation:
Pre-determined post-processing method: Spinning (for producing DTY), direct stretching weaving, or for specific color or functional products? Different processes have different requirements for the evenness of the filament structure, the elongation CV value, and the color stability of POY fibers.
Additional specification: Determine the fineness range (68D - 1800D) based on the requirements of the final product, and indicate whether color or functional masterbatch is needed.
Final sample test run: Conduct a small-scale trial on your winding machine or drawing equipment. Observe the breakage rate, tension fluctuations, and the appearance and feel of the finished silk. Confirm that it meets expectations before increasing the order quantity.
Ningbo Dazhong Industrial Fibre Co., Ltd. was founded in 1984. It produces 15,000 tons of products annually, including polypropylene POY yarn, polypropylene FDY yarn, polypropylene stretching yarn, and polypropylene coloured yarn. The fibre fineness ranges from 68D to 1800D. Please feel free to send samples for testing and discuss the requirements of the subsequent processes.
Official website: http://www.dzfibre.cn