Polypropylene fiber

Polypropylene fibers are categorized into long fibers, short fibers, spunbond nonwoven, meltblown nonwoven, etc.

Polypropylene long fibers can be divided into ordinary long fibers and fine-diameter long fibers (single fiber denier ≤ 2.2 dtex). They are suitable for producing clothing and decorative items, as well as some industrial long fiber products. Fine-diameter polypropylene long fibers offer good luster, soft feel, good drape, and low density, making them ideal for the knitting industry. When blended with cotton, viscose, silk, spandex, etc., to create products like cotton-polyester and silk-polyester blends, they are an excellent material for making sports attire, T-shirts, and more.

The production process of polypropylene short fibers mainly employs porous, low-speed, continuous processes, known as the short spinning process. Polypropylene short fibers can be blended with cotton to produce cotton-nylon fine fabrics, bed linens, and blankets. Blending fibers with viscose can create blankets, pure and blended polypropylene yarns, polypropylene blankets, carpets, and cigarette filters. The fiber thickness for hygiene products ranges from 1.5 to 2.5 dtex, while for ground fabrics, it is 5 to 10 dtex. The fiber length varies from 1.5 to 200.0 mm, depending on the application. Short fibers for concrete are typically 1.5 to 200.0 mm, for diapers usually 40.0 mm, and for ground fabrics, 60.0 mm.

Spunbond nonwoven fabric, also known as monofilament nonwoven, is made by melting polypropylene material, then extruding, spinning, stretching, laying, and bonding it into shape. It boasts short processes, low costs, high productivity, excellent product performance, and wide applications. Polypropylene nonwoven fabric is extensively used in various fields of production and daily life (such as disposable hygiene products, single-use protective clothing, agricultural fabrics, furniture fabrics, and shoe lining, etc.).

The fibers produced by meltblown nonwoven technology are extremely fine (down to 0.25μm). Meltblown fabrics have a large specific surface area and small pores with high porosity, which makes their filtration, shielding, and oil absorbency properties difficult to achieve with nonwovens produced by other individual processes. Meltblown nonwoven fabrics are widely used in hygiene, thermal insulation materials, and filtration materials, among other fields.

Features:

(1) Lightweight

Polypropylene fiber has a density of 0.90-0.92 g/cm3, making it lightest among all chemical fibers. It is 20% lighter than nylon, 30% lighter than polyester, and 40% lighter than viscose fiber, thus it is highly suitable for winter clothing filling materials or fabrics for ski and mountaineering gear.

High strength, good elasticity, wear-resistant, corrosion-resistant

High-strength polypropylene (equally in dry and wet conditions) is an ideal material for making fishing nets and ropes; it boasts good wear resistance and elasticity, with strength comparable to polyester and nylon, and rebound rates that can rival nylon and wool, far exceeding those of polyester and rayon. Polypropylene has poor dimensional stability, tends to ball and deform, is antimicrobial, and is not susceptible to moth damage; it also has superior chemical resistance compared to most fibers.

(3) Electrical insulation and thermal retention properties

Polypropylene fibers have a high resistivity (7×10^19 Ω.cm), low thermal conductivity. Compared to other chemical fibers, polypropylene exhibits better electrical insulation and thermal retention properties, but it is prone to generating static electricity during processing.

(4) Poor heat and aging resistance

Polypropylene fibers have a low melting point (165~173℃) and poor stability to light and heat, hence, they have poor heat resistance and aging resistance and are not heat-resistant. However, their anti-aging properties can be enhanced by adding anti-aging agents during spinning.

(5) Poor moisture absorption and dyeing properties

Polypropylene fibers have poor hygroscopicity and dyeability among chemical fibers, absorbing almost no moisture with a moisture regain rate less than 0.03%. Fine denier polypropylene has strong core wicking, allowing moisture vapor to be expelled through capillaries within the fibers. When made into clothing, the comfort is enhanced, especially with ultra-fine polypropylene fibers, which, due to their increased surface area, can transmit sweat more quickly, maintaining a comfortable skin feeling. As the fibers do not absorb moisture and have low shrinkage, polypropylene fabrics are easy to wash and dry quickly.

Polypropylene has poor dyeability, with light colors and poor color fastness. Ordinary fuels cannot dye it, and colored polypropylene is mostly produced by pre-dyeing during spinning. Liquid dyeing, fiber modification, and blending fuel ligands before melt spinning can be adopted.