1. What is Polypropylene Fiber?
Polypropylene fiber, also known as polypropylene fiber, is a synthetic fiber spun from isotactic polypropylene, obtained by polymerizing propylene.
Polypropylene fibers can be classified into long fibers, short fibers, spunbond non-woven fabrics, meltblown non-woven fabrics, etc.
Polypropylene long fibers can be divided into ordinary long fibers and fine denier long fibers (monofilament fineness ≤ 2.2 dtex, used in the production of clothing, decoration, and some industrial filament products). Fine denier polypropylene long fibers have good luster, soft hand feel, good drape, and low density, making them suitable for the knitting industry. When interwoven with cotton, viscose filament, silk, spandex, etc., to form cotton-covered polypropylene and silk-covered polypropylene products, they are ideal materials for making high-end sportswear, T-shirts, etc.
The production process of polypropylene short fibers mostly adopts a porous, low-speed, continuous process, i.e., short-spinning. Polypropylene short fibers blended with cotton can be made into polypropylene-cotton fabrics and bed sheets; blended fibers with viscose can be made into blankets; pure and blended polypropylene yarns, polypropylene blankets, carpets, and polypropylene cotton wadding for cigarette filters. The fiber fineness for hygiene products is 1.5-2.5 dtex, while the fiber fineness for floor fabrics is 5-10 dtex. Fiber length ranges from 1.5 to 200.0 mm. The length of the fiber varies depending on its intended use. Short fibers used in concrete range from 1.5 to 200.0 mm, while those used in ground coverings range from 60.0 mm.
2. Characteristics of Polypropylene Fibers
(1) Lightweight. The density of polypropylene fibers is 0.90-0.92. Polypropylene has the lowest g/cm3 content among all chemical fibers, being 20% lighter than nylon, 30% lighter than polyester, and 40% lighter than viscose fiber. Therefore, it is well-suited for use as filling material in winter clothing or as fabric for ski suits, mountaineering suits, etc.
(2) High strength, good elasticity, wear resistance, and corrosion resistance. Polypropylene has high strength (both dry and wet conditions), making it an ideal material for manufacturing fishing nets and ropes; it has good wear resistance and resilience, with strength similar to polyester and nylon, and a resilience rate comparable to nylon and wool, much higher than polyester and viscose fiber; polypropylene has poor dimensional stability, is prone to pilling and deformation, is resistant to microorganisms and moths; and has better chemical resistance than general fibers.
(3) It has electrical insulation and warmth retention properties. Polypropylene fiber has a very high resistivity (7×10¹⁹ Ω·cm) and a low thermal conductivity. Compared with other chemical fibers, polypropylene has the best electrical insulation and warmth retention properties, but it is prone to static electricity during processing.
(4) Poor heat resistance and aging resistance. Polypropylene fiber has a low melting point. (165~173℃) Polypropylene has poor stability to light and heat, resulting in poor heat resistance, aging resistance, and poor ironing resistance. However, its anti-aging properties can be improved by adding anti-aging agents during spinning.
(5) Poor hygroscopicity and dyeability. Polypropylene fiber has the worst hygroscopicity and dyeability among chemical fibers, almost no moisture absorption, and its moisture regain is less than 0.03%. Fine denier polypropylene has a strong wicking effect, allowing moisture to be expelled through the capillaries in the fiber. When made into clothing, the garment is more comfortable, especially with ultrafine polypropylene fiber, which, due to its increased surface area, can transfer sweat more quickly, keeping the skin comfortable. Because the fiber does not absorb moisture and has a low shrinkage rate, polypropylene fabrics are easy to wash and quick-drying.
Polypropylene has poor dyeability, resulting in light colors and poor color fastness. Ordinary dyes cannot dye it, and most colored polypropylene is produced by pre-spinning dyeing. Solution dyeing and fiber modification can be used, with dye complexing agents added before melt spinning.
