What are the common specifications of polypropylene hollow filament yarns? How to select the fineness, length and hollow degree?

Specification classification

polypropylene hollow filament yarns have a wide range of specifications, mainly distinguishing dimensions include fineness, cutting length, and hollow degree. At the same time, according to the molding process, they are divided into two major categories: continuous filament and short-cut fibers, which are suitable for different downstream weaving, filling, and filtration scenarios. The regular market categories cover various gradients and can be customized according to product requirements.

Fineness is the basic indicator for selection, representing the thickness of the single filament. Filament with a smaller fineness has a finer texture and a softer fabric, and is often used for filtering materials and close-fitting filling fabrics; filament with a larger fineness has better rigidity and stronger support, suitable for geotechnical, rope and cable, and protective base fabric products that require mechanical performance.

Cutting length is for short-cut polypropylene hollow filament yarns. Different lengths are suitable for different blending and carding processes. Shorter specifications are easier to be uniformly mixed with other fibers, reducing carding agglomeration, suitable for non-woven fabrics and filling cotton; longer specifications have better adhesion, better structure after weaving and netting, often used in engineering fabrics. Continuous hollow filament yarns do not need to be cut and can be directly woven on the machine, suitable for ropes, straps, etc.

Hollow degree represents the proportion of the internal cavity of the fiber, which is the core characteristic of hollow filament yarns. Higher hollow degree means the fiber is lighter and has better insulation and buoyancy effects, often used for thermal insulation filling and water-related products; products with an appropriate hollow degree balance mechanical stability, the cavity structure is less likely to be flattened during processing, suitable for geotechnical fabric and filter base materials; fibers with a lower hollow degree have a compact structure, better resistance to compression and wear, suitable for continuous force conditions.

Summary of selection

Selection cannot be based solely on parameters. It should be comprehensively judged in combination with the processing method and usage environment. For thermal insulation filling, hollow degree is the priority consideration; for filtering products, both fineness and length are taken into account; for engineering products, the stability of the fiber structure is the priority. At the same time, it is necessary to match the subsequent equipment. The compatibility of parameters for carding, needling, and spinning processes is different, and improper parameter matching may lead to problems such as broken yarns, flat holes, and uneven netting. 

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