Nonwoven fabric is a fabric-like material made from staple fiber (short) and long fiber (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted.
Different types of non-woven fabrics over-view
The non-woven fabrics can be divided into 8 types according to different manufacturing processes:
- Spunlace nonwovens
It is a non-woven cloth, it is the direct use of polymer slices, short fibers or filaments into a network of fiber by air or mechanical, spunlace, acupuncture, or hot-rolled reinforcement, and finally after finishing the formation of spunlace nonwoven fabric.
Application: It is well-known for its great uses for facial mask fabric, medical non-woven fabric, wet wipe fabric, non-woven filter fabric and etc.
- Heat-bonded nonwoven fabrics
This type of non-woven fabric is mainly manufactured in several processes: adding fibrous or sticky reinforcement material into the fiber network, and then reinforcing the network into cloth via heating and cooling.
- Pulp air-laid nonwovens
Air-laid nonwovens can also be called the dustless paper or dry paper nonwovens. It uses the air-laid technology to open the wood pulp fiberboard into a single fiber state, then uses the airflow method to make the fiber agglomerate on the net curtain, and then consolidates the fiber web into cloth.
- Wet-laid non-woven
The manufacturing process of wet nonwoven fabric goes like this: open the fibrous raw material in the aqueous medium into single fibers, meanwhile forming a fibrous suspension slurry by mixing different fiber raw materials, then transport the suspended slurry to a mesh-forming mechanism, and the fibers are laid in a wet state to form a cloth.
- Spunbond nonwovens
Spunbond-type of nonwoven fabric is processed as follows: extrude and stretch the polymer to form a continuous filament, laid the filament into web, then process the web into nonwoven fabric through their own bonding, thermal bonding, chemical bonding or mechanical reinforcement methods.
- Meltblown nonwovens
Melt-blown nonwoven fabric is manufactured by extruding melted polymer fiber through a linear die containing several hundred small holes to form long thin fibers which are stretched and cooled by passing hot air as they fall from the linear die, then the resultant web is blown onto a collector screen forming fined-filtered, self-bond nonwovens. Usually, this type of nonwoven fabric is added to spunbond in order to form SM or SMS webs.
- Acupuncture nonwovens
Acupuncture nonwoven is a type of dry nonwoven fabric. The fluffy fiber is reinforced into cloth by needle puncture.
- Stitch nonwovens
Stitched nonwoven is another type of dry nonwoven fabric. The manufacturing process uses a warp knitted loop structure to reinforce the fiber web, yarn layer, non-woven materials (such as plastic sheeting, plastic foil and etc.) or a combination thereof so as to form a nonwoven fabric.
Non-woven market: The non-woven fabrics market size is estimated to grow from USD 22.62 Billion in 2016 to USD 34.85 Billion by 2022. The market is projected to grow at a CAGR of 7.51% during the forecast period. The base year considered for the study is 2016, and the market size is projected from 2017 to 2022.
Manufacturing of non-woven fabric
Raw material: Raw materials of non-woven fabric are given in the flow chart.
Natural fiber: cotton, jute, linen
Regenerated fiber: Bamboo fiber, viscous fiber, Tencel, modal fiber.
Synthetic polymer: PP, PE, PET, NYLON, PA, polyester, PCL, PLA
The main way of making a nonwoven fabric
According to ASTM, felt is a structured build-up from the interlocking of fibers by a suitable combination of mechanical work, chemical action, moisture and heat without spinning, weaving, or knitting.
Other Felted Fabric Cotton felt, jute felt, Flax Felt, Synthetic Fiber Felt fabric.
Manufacturing process: Felt is manufactured either manually or by machine. Machine-made felt manufacturing is described in the following. Fiber is subjected to two consecutive carding operations and the two carding operations make the fibers parallel and of even thickness in the form of a fine web.
Several layers of web are built up until a sufficient amount of weight or thickness has accumulated. The mass or batt (layer of web) is then cut and the edges trimmed to the desired width. The batts are usually about 37m long, 150-230 cm width and their weights vary from 8-23 kg.
The batts are evenly sprinkled with warm water, pass over a steam box to warm the fabrics thoroughly and then press between two rollers.
The top roller rests on the batt and with an oscillating motion exerts the pressure that combined with moisture and heat produces the final felting action. Then they are allowed to draining and cooling off for about 24 hours.
Geo-Textiles: (Road construction, rail line Construction, River Bank Construction)
Mattress, foam, floor cover, composite.
Bonded non-woven fabric:
Nonwoven web formation methods are classified according to the form of raw materials chosen for the specific application. Staple fiber and filaments are used to fabricate nonwoven webs.
Bonded Non-woven techniques are:
- Polymer-melt/ spun-melt
Dry-laid web formation: Dry-laid web formation is one of the old techniques and is very similar to the felting process. For the production of dry-laid web, carding machines and web lappers are used to layer the fibrous batt. The fibrous web layers are subsequently felted using heat, moisture, and agitation. These materials may be of natural or synthetic polymer composition and can be processed alone or in blends. Carded webs are produced from either short-staple fiber (20–60 mm) or long-staple fiber (50–150 mm).
The dry-laid web formation technique, such as fiber preparation, blending, carding, and garnering are innovations of the textile industry. These processes prepare staple fibers, blend them, and layer the fiber batt in a dry state. In dry-laid web formation, the fibers are collected into a web form by parallel lapping, cross-lapping, or aerodynamic (air-laid) lap forming and then bonded by means of mechanical needles, hydro-entanglement, chemical adhesives, and thermal bonding methods.
Raw material: Cotton fiber, synthetic Fiber, Viscose fiber, Short cotton fiber.
Application of dry-laid
- Baby wipes
- Feminine Napkins
- Adult Incontinence Products
- Medical textile
Wet-laid web formation: Wet-laid forming, which can be regarded as being analogous to conventional papermaking processes but with use of chopped synthetic or staple fibers, continues to draw attention as an advantageous way to prepare advanced nonwoven textile products. The wet-laid web forming system is designed to fabricate short fibers dispersed in liquid, which are subsequently layered. The wet-laid method is specifically suitable for the large scale production of disposable products, such as tea bags, aprons, gloves, napkins, and surgical gauze.
Raw Material: A wide range of natural, wood pulp, mineral, synthetic and man-made fibers of varying lengths can be used such as glass, polyester, polyamide, and regenerated fiber.
Applications: Filter paper, Tea Bag Fabric, Napkin, Surgical gauze.
Spun-melt non-woven fabric: Spun-melt is a generic term describing the manufacturing of nonwoven webs directly from thermoplastic polymers. It encompasses 2 processes,
- Spun-bond Non-woven
- Melt-Blown Non-woven
Spun-laid (bonded) Non-woven: Polymer granules are extruded into filaments through so called spinnerets. The continuous filaments are stretched and quenched before being deposited on conveyor belt to form a uniform web. The spun-laid process results into nonwovens with an increased strength compared to carding, due to the attenuation of the filaments. The downside is that the choice of raw materials is more restricted. Co-extrusion of two components leads to bico fibers, either adding more properties to the web or allowing air-through bonding. Please note that the word spunbond is reserved for thermo bonded spun-laid.
Raw material: PP (polypropylene), Pet, Nylon, PE, Polyester. (Synthetic Thermoplastic Resin).
Application: Packaging (Shopping Bag), PPE for medical,
Melt-blown non-woven: Meltblown, like spun-laid, starts with extruding a low viscosity polymer. But instead of quenching the filaments when they leave the spinneret, the filaments are being attenuated by hot air streams, keeping the filaments in a partially molten state. This leads to much thinner filaments, with low tensile strength. The filaments hit a belt or a conveyor belt where they form a web.
Raw material: Polypropylene (PP), polyamide (PA), Polyester, Polyethylene (PE).
Some of the processed polymers are:
- Polypropylene is the most used polymer for melt-blown technology.
- Polypropylene is easy to process and makes good web.
- Polyethylene is more difficult to melt-blow into fine fibrous webs than is polypropylene.
- Polyethylene is difficult to draw because of its melt elasticity.
- PBT processes easily and produces very soft, fine-fibered webs.
- Nylon 6 is easy to process and makes good webs.
- Nylon 11 melt-blows well into webs that have very unusual leather-like feel.
- Polycarbonate produces very soft-fiber webs.
- Polystyrene produces an extremely soft, fluffy material with essentially no shot defect
Manufacturing process: The melt-blown technology is based on a melt blowing process, where, usually, a thermoplastic fiber-forming polymer is extruded through a linear die containing several hundred small orifices. Convergent streams of hot air rapidly attenuated extruded polymer streams to form extremely fine fiber (1-5 micro-meter). The attenuated fibers subsequently blown by high viscosity air onto a collector conveyor, thus forming a fine fibered self-bonded non-woven fabric.
Applications: Filter paper, N95 mask (as filter fabric), PP Gown, surgical mask, Napkin, Teabag fabric, water filter.
- Face Mask
- Silica gel bag
- Sanitary materials
- Warm filling material
- Filtering material
- Diapers and sanitary pads
N95 mask: An N95 respirator is a respiratory protective device designed to achieve a very close facial fit and very efficient filtration of airborne particles.
The ‘N95’ designation means that when subjected to careful testing, the respirator blocks at least 95 percent of very small (0.3 micron) test particles. If properly fitted, the filtration capabilities of N95 respirators exceed those of face masks. However, even a properly fitted N95 respirator does not completely eliminate the risk of illness or death. Surgical N95 Respirators are commonly used in healthcare settings and are a subset of N95 Filtering.
Manufacturing Technology: 5-layer Fabric.
Surgical mask: A surgical mask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. These are often referred to as face masks, although not all face masks are regulated as surgical masks.
- It is tested for fluid resistance, filtration efficiency (particulate filtration efficiency and bacterial filtration efficiency).
- It should not be shared or reused.
Raw material: 3layer surgical mask make by SMS fabric.