PP Spunbond nonwoven fabrics are classified as nonwovens composed of endless filaments, and produced by an integrated process combining fiber spinning, web formation, and bonding. The fabrics are produced by depositing extruded, spun filaments onto a collecting belt, followed by bonding the fibers.
A primary factor in the production of spunbonded webs is the control of four simultaneous, integrated operations: filament extrusion, drawing, laydown, and bonding. The first three operations are directly adapted from conventional manmade fiber spinning and constitute the spun or web formation phase of the process. The fibers are separated during the web laying process by air jets or electrostatic charges. The collecting surface is usually perforated to prevent the air stream from deflecting and carrying the fibers in an uncontrolled manner. The last operation is the web consolidation or bond phase of the process- hence the generic term spunbond. Bonding imparts strength and integrity to the web by applying heated rolls or hot needles to partially melt the polymer and fuse the fibers. In its simplest form, a spunbond line consists of the following elements: an extruder for forming filaments; a metering pump, a die assembly, a filament spinning, drawing, and deposition system, a belt for collecting the filaments, a bonding zone, and a winding unit.
Righr now nonwoven fabrics are being used in a great variety of products as listed below. The key to most of these markets has been a low cost covering material with sufficient tensile properties to fit the application.
- Agriculture: Plant cover, inner curtains in green house
- Apparel: Interlinings, high-loft insulation, protective clothing, embroidery backings
- Automotive: One of the major uses of spunbonded webs in automobile is as a backing for tufted automobile floor carpets. The spunbonded webs are also used for trim parts, trunkliners, interior door panel, and seat covers
- Construction and civil engineering: the segment remains a large market for spunbond webs, constituting sometimes closer to 25% of the total. Spunbonded civil engineering webs cover a multiple of related uses, such as, erosion control, house wrap protection, railroad beds stabilization, canal and reservoir lining protection, highway and airfield black top cracking prevention, roofing (upper sheet), etc. The particular properties of spunbonded webs - which are responsible for this revolution - are chemical and physical stability, high strength/cost ratio, and their unique and highly controllable structure which can be engineered to provide desired properties.
- Geo-synthetics: earth reinforcement, tunnel drainage, soil separation
- Household: bags, wrapping paper, carpet backing, furniture dust covers
- Industrial: cable sheath, battery separator, air and liquid filters
- Medical and sanitary/hygienic: the use of spunbond web as a coverstock for diapers and incontinence devices is still growing dramatically. This is mainly because of the unique structure of spunbond, which helps the skin of the user stay dry and comfortable. Additionally, spunbond webs are cost effective over other conventional nonwovens. Spunbond web, as coverstock, is also widely used in sanitary napkins and to a limited extent in tampons. In medical applications many traditional materials have been replaced by high performance spunbonded webs. The particular properties of spunbonded webs, which are responsible for medical use are: breathability, resistance to fluid penetration, lint free structure, sterilizability, and impermeability to bacteria. Medical applications include: disposable operating room gowns, shoe covers and sterilizable packaging, incontinence devices, medical wipes, medical gowns, drapes and barrier fabrics
- Packing: Spunbond fabrics are widely used as packaging material where paper products and plastic films are not satisfactory. The examples include: metal-core wraps, sterile medical packaging, floppy disk liners, high performance envelopes and stationery products.