Non-woven fabrics are made of bonding fibres together by chemical, heat, mechanical or solvent treatments. Both staple fibres (short) fibres and continuous long fibres are used in non-woven materials. It is basically a sheet of fibres (staple and continuous), that have been formed into a web, bound together by various means, other than weaving or knitting. The term non-woven was coined in 1942 and were first were known to be produced in the US. The first non-woven fabrics were formed by adhesively bonding fibre webs together.
Manufacturing processes for non-woven
Non-woven fabrics are typically made by putting small fibres in a form of a sheet or web, and binding them together in that form, through various mechanical, adhesive, thermal, solvent, or chemical treatments. The choice of manufacturing process depends on the properties required in the final product. There are mainly four manufacturing processes used to produce non-woven, namely:
- Spun-bond/ Spun-laid process: This process includes melting of raw material, which are formed into filaments then laid as a web, to be bound together by using heat rollers and embossing.
- Melt blown process: In this process also, polymer fibres are melted, stretched into long thin fibres, and formed into a web, which is then bonded together. The only difference between this process and the spun-bond process is that the melt-blown process produces non-woven fabric with low intrinsic strength but offers much smaller size, which can be used for certain applications.
- Needle punching process: This process is mainly used for manufacturing felt. Here, fibres used are interlocked together by using serrated needles to increase the inter-fibre friction, which gives stronger strength in the resultant fabric.
- Spun-Lace (Hydro-entangling) process: This process uses a high-pressure liquid stream to bond the fibre web together and impart a pattern to the resulting fabric. Here, staple fibres (e.g. cotton) are formed into a dry laid web, by carding operation. This web is then passed through a high-pressure liquid stream, which in turn entangles the staple fibres, forming the non-woven fabric.
Difference between Wovens and Non-Wovens
The production process of nonwoven fabrics is much smaller than that of woven fabrics, making nonwovens comparatively less expensive to produce. Moreover, the fabric structure of woven fabrics provides it much more default durability and strength, as compared to nonwoven fabrics, although the choice of raw material will also affect these properties. Nonwoven fabrics are mostly used for interlining or to make hats or other handicrafts.
Applications of non-wovens
The properties of nonwovens depend highly on the fibre characteristics, its processing conditions, and the bonding and finishing process and materials used. Due to their unique fabric structures, nonwovens find numerous applications in varied fields. Nonwovens are also treated as alternatives for technical textiles and geotextiles in many industries, especially in healthcare and automotive industries.
Nonwovens fabrics can be specially engineered to suit different applications. Some of the most common applications of nonwoven fabrics are in:
The Manufacturing Process for Non-Woven Fabrics includes the following steps:
- Medical field: medical field sees multiple uses of various nonwovens. It is used in manufacturing isolation and surgical gowns, drapes and covers, masks, scrub suits, caps, gloves, shoe covers, wipes, etc. nonwovens are also used in medical packaging as their porosity can permit gas sterilization. It is used in making wound dressings, plasters, and also in drug delivery.
- Nonwoven fabrics are highly used in the modern, disposable, absorbent hygiene products, which has substantially improved the quality of life for millions, globally. In medical use, nonwoven fabrics find their use in surgical (both implantable and non-implantable), extracorporeal and healthcare and hygiene products. Nonwoven fabrics are also used in making artificial skin, wound contact layer, scaffold plasters, wadding, elastic, non-elastic and compression bandages and gauze dressings.
- Filtration: Nonwoven fabrics are suited for use in gasoline, oil and air filtration. They are used as filters for water, as tea bags and coffee filters, in the pharmaceutical industry, in mineral processing, as liquid cartridge and bag filters, as vacuum bags, etc.
- Geotextiles: In geotextiles, nonwoven fabrics are often used as sandbags for soil and foundation stabilization, road underlayment, in drainage systems, for erosion control, etc. Compared to woven fabrics, nonwoven fabrics are more robust, and hence, are used more in erosion prevention projects.
- Others: Apart from the specific medical and geotextiles uses, nonwoven fabrics are used often in diapers, feminine hygiene projects, in packaging, insulation, upholstery padding, sleeping bags, surfboards, etc.
Nonwoven fabrics hence find their application in fields of hygiene, agriculture, building, civil engineering, upholstery, filtration, medical, floor covering, interlinings, and footwear, technical textiles, garments and coating substrates.
Advantages of Non-wovens
The biggest advantage that nonwoven fabrics offer is the vast versatility that engineering changes can bring in to their properties. Nonwoven fabrics are dynamic and cheap at the same time, making them ideal for use in many functions, especially in the fields which require single-use disposables like medical applications.
The various advantages that nonwoven fabric offers over its woven and knitted counterparts are:
- Better uniformity
- Higher tensile and tear strengths
- Form holding capabilities in the Z direction
- Dimensional stability
- Application specific engineering
- Consistent performance even at high temperatures
- Customized product development capabilities
- Cost-effectiveness both at high and low volume production runs
- Ability to form composites required for higher performance
The future of Nonwovens
Nonwoven fabrics have reported one of the highest growth rates in the textile fields in recent times. Over the past decade, the use of textile fibres in nonwoven fabrics has highly surpassed the fibre used in other forms of textile products (woven, knitted, etc.).
Technological advancements, recent product developments, and growing consumer awareness are adding to the popularity of nonwovens globally. Medical and hygiene industries are also growing their adoption of nonwoven products.
The Asia-Pacific region is expected to provide a major role for the nonwovens market primarily due to emerging economies in China and India, accompanied with growing awareness among customers.
The global nonwoven market value in 2015 was at $37 bn and is expected to grow up to $50 bn in 2020. Asia has already emerged as the biggest consumer for nonwoven fabrics, overtaking Europe and American in the past decade. Amongst all the nonwoven varieties, spun-laid nonwovens remain the most demanded nonwovens, owing to their massive use in medical textile fields. By 2020, the spun-laid nonwoven fabric consumption is predicted to reach up to 6.3 mn tonne globally. [5]
In the coming future, disposable nonwovens are expected to experience a higher growth than durable nonwovens.
Because the raw materials used for production of nonwovens mostly include synthetic polymers and fibres. They represent more than 90 per cent of overall output. Currently, polypropylene (PP) is the major raw material used for global nonwovens.
Polypropylene is the largest used raw material in nonwoven production. There is hence a tremendous growth opportunity in this segment.
