Non-woven fabrics: manufacture and web formation
Non-wovens are made directly from fibres, skipping yarn. A web is formed (parallel, cross, random-laid or sprayed), then bonded mechanically, chemically or by heat.
Draw it: making a non-woven
Web formation methods
| Method | How the web is laid | Result |
|---|---|---|
| Parallel-laid | Several carded webs are laid one over another, with fibres along the machine direction | Strong lengthwise, weak across |
| Cross-laid | A carded web is folded back and forth across a moving belt by a cross-lapper, so the layers lie at an angle | Better strength across; wide, thick webs |
| Random-laid | Fibres are blown by air onto a screen (air-laid) or settled from water (wet-laid), lying in all directions | About equal strength in every direction |
| High-velocity sprayed | Fibres or molten polymer are blown at high speed through jets onto a moving belt; in melt-blowing, very fine fibres stick together as they cool; spun-laid webs lay filaments straight from the spinneret | Very fine, even webs: mask filters, gowns, wipes |
Bonding the web
| Method | How | Examples |
|---|---|---|
| Needle punching | Barbed needles push through the web many times, entangling the fibres | Needle felts, carpet underlay, blankets, geotextiles |
| Hydro-entangling (spunlace) | Fine, high-pressure water jets tangle the fibres | Wet wipes, soft medical gowns and drapes |
| Stitch-bonding | Rows of stitches are knitted through the web | Furnishing, cleaning cloths |
| Chemical (adhesive) bonding | The web is soaked, sprayed or printed with a binder such as latex, then dried | Interlinings, disposable napkins |
| Thermal bonding | Heated rollers or hot air melt thermoplastic fibres where they touch | Carry bags, diaper cover-stock, crop covers |
Uses of non-wovens
- Medical: surgical masks (melt-blown filter layer), gowns, caps, drapes, shoe covers, wound dressings.
- Hygiene: diapers, sanitary napkins, wet wipes.
- Clothing: fusible interlinings in collars and cuffs, shoulder pads.
- Home and food: tea bags, coffee filters, kitchen wipes, disposable table covers, carry bags.
- Industry and farming: geotextiles for roads, filters, crop covers, insulation.
Non-wovens are everywhere in food service and hospitals: disposable caps, masks and aprons for food handlers, tea bags and filters, and spunlace wipes for cleaning counters. Most are single-use, so discard them as the unit's waste rules require.
2 marks: “Define non-woven fabric.” A fabric made directly from a web of fibres or filaments held together by mechanical, chemical or thermal bonding, without weaving or knitting.
5 marks: “Explain the methods of web formation.” Parallel-laid, cross-laid, random-laid (air-laid, wet-laid) and high-velocity sprayed (melt-blown, spun-laid): how each is laid and the strength it gives.
10 marks: “Describe the manufacture of non-woven fabrics, with their uses.” Flow chart; fibre preparation; web formation methods; bonding methods (needle, water jet, stitch, adhesive, thermal); finishing; uses in medicine, hygiene, clothing, home and industry.
Non-woven = web + bond. Webs are P-C-R-S, 'Please Cut Rice Slowly': Parallel, Cross, Random, Sprayed.