The polypropylene double-twist yarn is not suitable. This will greatly affect the weaving efficiency - two key issues need to be clarified first. 

polypropylene double-twist yarn (high-strength polypropylene double-twist yarn) is a type of yarn formed by twisting and combining two or more strands of polypropylene filaments. It is widely used in webbing, industrial fabrics, sewing threads, cable ropes, and other fields. Many purchasers often encounter confusion when choosing the right type: even though they call it double-twist yarn, some have knots during weaving, and some have uneven strength. Let's address two common issues below to help you clarify your thinking. 

1. Twist and Twist Direction: How to Match Your Application? 

Twist (the number of twists per meter) and twist direction (S twist or Z twist) are the core parameters of double-twist yarns, directly influencing the strength and weaving performance of the yarn. 

Twist selection: When weaving warp yarns, a higher twist is usually required to enhance the wear resistance of the yarn and reduce fraying; for weft yarns or sewing threads, a moderate twist is sufficient. An excessively high twist will make the yarn stiff and make it difficult for knots to loosen when they form. When purchasing, you can inform the supplier of your loom type and fabric structure, and the supplier will recommend an appropriate twist range. 

Twist direction matching: For single yarns, Z twist or S twist is usually adopted. When used for plaiting or weaving, it is necessary to pay attention to the twist direction coordination between the warp yarn and the weft yarn. Otherwise, the fabric surface may present weft skew or knotting. For double-twist yarns used in sewing, the twist direction is usually required to match the rotation direction of the sewing machine to reduce the twisting of the thread loop. 

II. Raw Materials and Number of Combined Strands: Key Factors Affecting Strength and Appearance 

The performance of double-twisted yarn is not only determined by the twisting process, but also depends on the quality of the raw yarn and the number of combined strands. 

Raw material grade: The ordinary polypropylene filament FDY double-twisting process results in ordinary strong double-twisting filament; the high-strength polypropylene filament double-twisting process yields high-strength polypropylene double-twisting filament. For load-bearing scenarios such as lifting belts and ropes, it is recommended to choose high-strength polypropylene double-twisting filament; for ordinary luggage straps and clothing accessories, the ordinary strength specification is sufficient. 

Number of strands combined: When combining two strands, it is necessary to ensure that the tension and length of the two strands are consistent. Otherwise, after twisting, the "long and short strands" phenomenon will occur, resulting in uneven strength. The double-twist or triple-twist yarns used for sewing threads usually adopt two or three strands combined, and it is required that the surface hairiness is low and the knot strength is high. 

Color and uniformity: When using colored double-twisted yarns, it is necessary to pay attention to the color differences of multiple strands. The colors of different sections of the same bobbin should be consistent, and the color differences between different bobbins should be controllable. It is recommended to ask the supplier to provide sample rolls of recent batches for comparison during the purchase process. 

Summary and Selection Suggestions 

When purchasing polypropylene double-twisting yarn (high-strength polypropylene double-twisting yarn), it is recommended to confirm the following steps: 

Designated purpose: To weave warp yarn, weft yarn, sewing thread or cable rope? Different purposes have different requirements for twist degree, twist direction, number of strands and strength. 

Additional specification: Inform the target denier (total denier), ply count, whether high strength is required, and whether color addition is needed. 

Final sample test: Conduct a small-scale trial on your loom or sewing equipment to observe the breakage rate, knotting situation, and the surface effect of the finished product. 

Guangdong Montai High-tech Fiber Co., Ltd. specializes in the production and research of polypropylene FDY network yarn, polypropylene network yarn, and polypropylene double-twist strong yarn. We welcome sample requests for testing. 

Declaration: The content and template of this article are sourced from the internet and are copyrighted by the original authors; any infringement will be promptly notified and deleted upon contact. 

Guangdong Modern High-tech Fiber Co., Ltd.  Official Website: http://www.gdguangdong.com