Polypropylene fiber grade holds an absolute dominant position in the nonwovens industry, serving as its most widely used and consumed synthetic fiber raw material. From everyday diapers and masks to geotextiles supporting modern infrastructure and medical supplies protecting our health, polypropylene nonwovens play an indispensable role. With technological advancements, its applications in high-end filtration, smart textiles, and sustainable materials will continue to expand.
Why is fiber-grade polypropylene so popular in the nonwovens industry?
1. Excellent physical and mechanical properties
Low density and lightweight. With a density of only 0.90-0.91 g/cm³, it is the lightest of common fibers (for comparison, polyester is approximately 1.38 and nylon is approximately 1.14). This means that the same weight of raw material can produce more volume or area, offering excellent coverage and cost-effectiveness. The resulting fabric is lightweight and comfortable.
High strength and toughness. It exhibits excellent tensile strength and impact resistance, and is particularly resistant to abrasion and fatigue. The resulting fibers and nonwovens are durable and can withstand the stresses of subsequent processing and use.
Excellent resilience. Fiber-grade PP products offer excellent wrinkle resistance and shape retention, and are not susceptible to permanent deformation.
2. Chemical Stability
Excellent chemical resistance. It exhibits excellent resistance to most inorganic chemicals, such as acids, alkalis, and salts, as well as organic solvents, and is insoluble in all solvents at room temperature. This makes it irreplaceable in applications such as filter materials, chemical protective clothing, and industrial wipes. It is also mildew-resistant and moth-resistant.
Excellent hydrophobicity. The molecular chain contains no polar groups, resulting in extremely low hygroscopicity, with a moisture regain of almost zero under standard conditions. The fabric dries quickly and does not gain weight due to moisture absorption. It is ideal for use in the topsheets and backsheets of diapers and sanitary napkins, keeping skin dry and preventing liquid leakage.
3. Processability is key to its popularity
Excellent melt processability. With a melting point between 160℃ and 170℃, low melt viscosity, and excellent fluidity, it is well-suited for processing through mainstream processes such as melt spinning, spunbond, and meltblown, offering relatively low energy consumption and high production efficiency.
Excellent thermal bonding properties. As a thermoplastic polymer, it can be softened by heating near its melting point and then resolidified and bonded under pressure or after cooling. This is the basis for hot-through-bonding and hot-calendering nonwoven production processes. Requiring no chemical adhesives, the production process is environmentally friendly, and the resulting product is fluffy and soft, making it particularly suitable for hygiene products.
4. Safety and Hygiene
Non-toxic and odorless. Complies with regulatory requirements for food and drug contact materials. It can be directly used in the production of food packaging, restaurant filter paper, medical and hygiene products, and infant products.
Skin-Friendly. Polypropylene’s chemical inertness makes it less susceptible to skin allergies, making it an ideal material for products that come into direct contact with the skin.
5. Economical and Environmentally Friendly
Low raw material cost. Polypropylene is one of the most competitively priced commodity petrochemicals. Using it as a raw material makes the final fiber and nonwoven products extremely cost-effective, driving its popularity in large-scale applications such as disposable products.
Recyclability. As a thermoplastic, production waste and post-consumer PP fiber products can theoretically be recycled and pelletized for use in the production of less demanding plastic products.
What Are Main Processing Techniques for Polypropylene in the Nonwoven Fabric Industry?
Spunbond. Molten PP is extruded through a spinneret to form filaments, which are then stretched and laid into a web. This process is then consolidated into fabric through hot calendering or needle punching. This process offers the highest production volume and widest application, resulting in high-strength and comfortable fabrics.
Meltblown. Molten PP is ejected through a special die, where it is stretched by high-velocity hot air into ultrafine fibers. These fibers then condense onto a web and self-bond to form fabric. Meltblown fabrics have extremely fine fibers and excellent filtration, barrier, and oil absorption properties, but they also have relatively low strength.
Spunbond and meltblown composite technology. It combines a spunbond layer (S) for strength with a meltblown layer (M) for barrier and filtration, leveraging their strengths and complementing their weaknesses. These composites are widely used in medical protective clothing, surgical drapes, and high-end hygiene materials.
Thermobonding. This includes hot-through bonding and hot calendering. A web or web of PP staple fibers is heated to melt-bond the fibers at their intersections. Commonly used in the production of soft, fluffy sanitary products, such as the topsheet and distribution layer of baby diapers and feminine hygiene products.
Needlepunching. The barbs of the needles entangle and reinforce the fibers in the web. Commonly used to produce thicker materials, such as geotextiles, carpet backing, and filter materials.
Hydroentanglement. Although PP is not as commonly used as cotton due to its hydrophobicity, it can be modified and used in the hydroentanglement process to produce products such as wipes.
What are the applications of fiber-grade polypropylene in the nonwoven fabric industry?
1. Healthcare Industry
Disposable sanitary products
Baby diapers, pull-on pants, feminine hygiene products, and adult incontinence care products. Used as the topsheet (for direct skin contact and rapid fluid distribution), distribution layer (to guide liquid diffusion), backing layer (waterproof and breathable), and side flaps.
Medical protective equipment
Protective clothing and surgical gowns. Using SMS (spunbond-meltblown-spunbond) composites, the spunbond layer provides strength and the meltblown layer provides barrier properties, effectively protecting against blood, body fluids, and microorganisms. Surgical drapes & sheeting. Used to cover non-surgical areas during surgery, requiring sterility and effective barrier properties.
Disinfectant wraps, hats, and shoe covers, etc.
Masks
Main layer. Spunbond nonwoven fabric, providing structural support and comfort.
Core filter layer. Meltblown nonwoven fabric, traps small particles, viruses, and bacteria through electrostatic adsorption. This is the most critical component of the mask.
2. Filtration and separation fields
Polypropylene’s chemical stability and ability to be made into ultrafine fibers through the meltblown process make it an ideal filter material.
Air filtration
Industrial dust masks (such as N95 and KN95). The core filter material is PP meltblown fabric.
Home and commercial air purifier filters.
HVAC (heating, ventilation, and air conditioning) system filters.
Automotive cabin air filters.
Liquid filtration
Water treatment filter cartridges & filter bags.
Food and beverage industry filtration.
Chemical and pharmaceutical industry filtration.
3. Geotechnical and construction fields
This field requires materials with corrosion resistance, high strength, and long life.
Geotextiles. Used in civil engineering projects such as roads, railways, dams, tunnels, and landfills. They enhance soil stability, prevent mixing of different soil layers, and allow water to pass through, thereby preventing soil erosion and drainage.
Construction materials. Base fabric for roofing waterproofing membranes, cladding for wall and roof insulation, sound-absorbing materials, and moisture-proof membranes for houses.
4. Packaging and Home Furnishings
Packaging materials. Eco-friendly bags, packaging linings for electronics, luxury goods, and clothing, composite cement bags, etc.
Home Furnishings
Furniture accessories. Sofa and mattress linings, spring coverings, and furniture backings.
Home Furnishings. Luggage and handbag linings, curtains, bedspreads, and pillow fillings.
Carpets and rugs. Carpet base fabrics and backings.
5. Wiping and Cleaning
Personal care wipes. Baby wipes, makeup remover wipes, and personal cleansing wipes. PP nonwovens, typically produced using hydroentanglement or air-through methods, are soft and skin-friendly.
Industrial and household wipes. Used for cleaning machines, countertops, glass, etc., with excellent liquid absorption and strength.
6. Apparel and Agriculture
Clothing accessories: interlining, thermal insulation sheets, disposable protective clothing.
Agricultural fabrics: harvest cloth, weed control cloth, greenhouse covers, and plant protection cloth.