18 Non-woven – I

B. A. Muralidhar

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Non-woven are unique engineered textiles manufactured by high speed and low cost processes which offer cost effective solutions in health care, geotextiles, filters etc. The manufacturing of non-woven is based on the technologies of plastics, paper and textile manufacture, as such, the properties and structure of the non-woven materials resemble these three materials. To a common man non-woven is something which is not a traditional woven materials. It is a sheet of individual fibres bonded intermittently along the length.


Nonwoven industry is one of the fastest growing industries, rapidly developing sophisticated and diverse products worldwide. The industry has been growing at an average of 10% over the past few decades. This growth rate are extremely high compared with the conventional textile industry. The significant developments and improvement


in most of the downstream manufacturing technology had enabled nonwoven manufacturers to produce acceptable materials with special properties at a very reasonable price and in quick time. The applications of non-woven are vast, some of the common products include:

  • Interlinings
  • Filters
  • Disposable sanitary napkins, nappies, tampons
  • Caps, gowns, masks etc. used in medical field
  • Automotive upholstery
  • Agricultural coverings
  • Wipes, bags, tags etc.

At the end of this session you will be able to

  • understand the difference between non-woven and other textiles
  • understand the manufacturing process of non-woven and
  • know about the properties and its applications

Worldwide the terms used to designate non-woven fabrics were in most languages in opposition to the woven textiles, and an average person is unlikely to be familiar with it. However, only the specialists would know that non-woven were exceptional engineered textiles developed to impart special properties to the product.


Generally, nonwovens can be defined as textile structures made directly from fibres in the form of batts, webs or continuous filaments bonded using various techniques including mechanical interlocking by needling or fluid jets, adhesive bonding, thermal bonding and stitch bonding.


The formal (ISO 9092) definition of Non-woven which has been adopted by the EU indicates that a nonwoven is a fabric made of fibres, that is consolidated in different ways.


As per ASTM a non-woven is defined as “a textile structure produced by bonding or interlocking of fibres, or both, accomplished by mechanical, chemical, thermal or solvent means and combinations thereof. The term does not include fabric or paper which are knitted, tufted, woven or those made by wool or other felting processes.” Non-woven are engineered structured sheets made by bonding and entangling fibres by means of chemical, mechanical of thermal processes. This technology has interested many industrialists and researchers because it totally omits the yarn manufacture process and its production are very high. Nonwoven application are mainly in the domain of Technical Textiles such as filtration, wipes, health care, geotextiles, face masks, automotive textiles, surgical gowns etc. The stages involved in the manufacture of non-woven are schematically illustrated in Figure.1


a) Fibre preparation

b) Web formation process

  • Dry laid system with carding of air laying (to form the web);
  • Wet laid system:
  • Polymer-based system (Spun bonding, Melt blown)

c) Web bonding and

d) Finishing process

                                       Figure 1. Schematics of nonwoven manufacturing




Fibres are the basic components used in the manufacture of nonwoven, almost any type of fibre can be used including natural/synthetic, as well as other hi-tech fibres. The fibres can be in the form of staple fibre, filament of yarns. The selection of the fibres, to a large extent determines the final property of the nonwoven in addition to the adhesives, bonding methods.


Conventional natural staple fibres, manmade fibres and bi-component fibres are mostly used in the preparation of carded nonwovens. However, almost all types of fibres can be used to produce nonwovens. The choice of fibres depends on the cost  effectiveness and application. The fibre preparation for web formation include processes such as fibre opening, mixing, and feeding to card or air-lay machines. During the web formation, many such card webs are stacked to form a web taking into account the required length wise and width wise uniformity, fibre mass, fibre distribution etc. Largely, the card webs have a length wise orientation meaning that the web strength is considerable greater in the machine direction than in the transverse direction.


The prepared web is stacked in three ways parallel-lay process, cross-lay process, and perpendicular-lay process.


4.1 Parallel-laid webs


In the parallel-lay (longitudinal layering) process the carded web is preferentially oriented in the carding machine direction i.e. the lengthwise orientation. In this process more than one card are placed in tandem and the carded webs from each cards are collected and laid one above the other on a conveyor belt. In this process, widening of the web width is not possible. The web width is same as the card web width and the number of web layer determines the number of cards needed to produce the web. Mostly the continuous methods are preferred in the parallel lay process.


4.2   Cross-laid webs


Cross-lay process is popular among non-woven industries. The objective of cross-ply is to obtain higher width, higher weight than that of card web, and to obtain web with fibres oriented along the transverse directions.


In this process, the web former/cross lapper which is placed inside the web, outside the card. Takes up the card web at a predefined rate and lays it over the conveyor belt system with an oscillating carriage. This take-off belt works at 90-degrees to the oscillating carriage (Figure 2.). By varying the speed ration of the oscillating carriage and the delivery conveyor the following variations can be brought about:

  1. The web mass can be increased.
  2. The web widths can be increased.
  3. Fibre orientation in the card web can be varied to improve the strength in the transverse direction.

FIGURE 2. Cross lapper


4.3 Perpendicular-laid webs


Perpendicular-lay process with the fibrous high lofts is a special laying process to obtain z-directional fibre orientation. This technique has an advantage over both parallel and cross lay because of the perpendicular fibres. The bonded webs have higher resistance to compression and show better resiliency.


In this process the carded web is fed to the vibrating or rotating perpendicular lapper situated over the conveyor. Fibre layer of desired density and thickness is produced on the conveyor and then the bonding process is accomplished. A reciprocating perpendicular lapper is shown below in Figure 3. This lapper produces the high loft fibre layer (6) on the conveyor belt (3) by folding the carded web (2). Thus a perpendicular laid fibre layer is created.

FIGURE 3. Reciprocating perpendicular lapper


Non-woven textiles are built on the fibrous web and its features and physical properties are largely dependent on the method of web formation and on the web geometry.


Web features are influenced by fibre length, fibre diameter, web weight and mechanical and chemical properties of the polymer.


Whereas, the web geometry is predominantly influenced by fibre orientation, fibre direction, fibre shape, fibre entanglement, crimp and z-direction compaction.




In this method, the fibrous web is formed by conventional spinning (roller cards). The staple fibres from the bale are opened both mechanically and pneumatically. The main objective of opening is to reduce the fibre tuft size. Further blending of fibre tufts from different bales also takes place in the process of opening and mixing. Then the opened fibres are transported to the feed box by air to the card frames. In the carding process, small fibre tufts are further individualized and parallelized, the carding action holds and combs the fibres causing fibre separation. These fibres are then condensed to form a lap or batting. Then the fibrous web is doffed from the cylinder and deposited on a moving belt.




In this method, the orientation created by carding is effectively improved by capturing fibres on a screen from an air-stream. Randomization excludes any preferred orientation when the fibres are collected on the condenser screen. This web is them delivered to a conveyor for transporting to the bonding area. Air laying is suitable for fibre length in the range of 2-6 cm, shorter fibre length allows for higher speed. Air laying is expensive and slower than carding.


Some of the advantages of Air-layed webs:

  1. Isotropic web can be produced
  2. Voluminous/bulky web can be produced
  3. Wide variety of synthetic and natural fibres can be processed


  1. Possible fibre entanglement in the air stream
  2. Lower level of fibre opening
  3. Variable web width structure

5.3 RANDOM CARD (Centrifugal dynamic web formation)


In this method the centrifugal dynamic random card forms the web by throwing off the fibres from the cylinder onto a doffer with centrifugal force. The production is higher than conventional cards. Fibre orientation in the web is random and three dimensional. The cross direction strength is better than machine direction w.r.t. conventional cards




Around 10% of the nonwovens are made by this method. Which is a modified paper making process. Its features are high production rates and the ability to blend a variety of fibres from papermaking technology. However, stiffness brought about by  using textile fibres in this technology has to be overcome to compete with other nonwoven products.

Stages in the manufacture of wet laid method:


a) Dispersion, swelling of fibres in water and transport of the suspension on a continuous travelling screen

b)  Filtration and continuous web formation on the screen

c)  Drying and bonding


Fibre suitability for the wet laid process depends on fibre fineness, fibre stiffness, crimp, wettability and its ability to disperse in an aqueous medium. Dispersed and swollen fibres are continuously fed to the web laying machine. Often, squeezing machine are used to dehydrate the web. The web is then compressed at the same time and subsequently bonded.


6. Spun-bond non-woven


Spun-bond non-woven is a polymer laid non-woven Figure 4. This concept was introduced by Reed in 1943. In this process, first the polymer (both thermoplastic and non-thermoplastic fibres) is extruded into filaments and attenuated. After attenuation the filaments are forwarded to a surface where the web is formed, this web is further bonded either thermally or chemically. The extruded spun filaments are collected on a belt. The collecting surface is perforated to prevent the air stream from deflecting and carrying the fibres in an uncontrolled manner. Strength and integrity to the web is imparted on bonding. Spun bonded non-woven have superior strength and less flexibility. Under application of thermal energy the polymer flows to the cross over points where bonding’s are formed, this bonding is fixed by subsequent cooling.

FIGURE 4. Spun bonding machine


The critical steps during bonding are:

  •  Heating the fibrous web to partially melt polymer crystalline region across fibre-fibre interface and
  •  Cooling of the web to solidify and trap the diffused fibre-fibre cross over points.

The spun bond process utilises both thermoplastic and non-thermoplastic blends containing carrier fibres and binder fibres. High molecular weight and broad molecular weight distribution polymers can be processed by spun bonding to produce  uniform webs. Binder fibre component normally ranges from 5 – 50 % on the weight of the non-woven.


In calendar bonding process (thermal), the fibrous web is passed through the nip of two rollers pressed against each other. The calendar roller may be embossed or flat depending on the type of bonding required like point bonding, stick bonding, grid bonding and area bonding.




Spun bonded webs are manufactured in a wide range ranging from very light, flexible structure to heavy and stiff structures. Their properties fall in between paper and woven fabric.

  1. Spun bonded webs possess random fibrous structure
  2. They possess high strength to weight ratio compared to other nonwovens
  3. Their liquid retention capacity is high due to high void contents
  4. They possess high in-plane shear resistance with low drape ability
  5. Web thickness ranges between 0.1 to 4.00 mm.
  6. Spun bonded non-woven are characterized by tear, tensile, elongation to break, bursting strength, weight, thickness and porosity etc.


  1. Automotive – spun bonded webs find many different applications in the automobile industry, such as floor carpet backing, interior door panel, seat covers, trim parts and trunk liners.
  2. Civil engineering – this market segment is the largest single market consuming over 25% of the total spun bonded materials produced. Civil engineering applications include canal and reservoir lining protection, airfield and highway black top cracking prevention, railroad beds stabilization, soil erosion control, roofing etc.
  3. Medical – many traditional materials have been replaced by high performance spun bonded webs which include sterilisable packaging, operating room gowns, shoe covers etc.
  4. Sanitary – Spun bonded webs because of their unique structure, is used as a cover stock for baby diapers, incontinence and tampons which helps the skin to stay dry and comfortable.
  5. Packaging – Spun bonded webs are used as packaging materials where paper and plastic are not satisfactory like metal-core wrap, high performance envelops, stationary, medical sterile packaging etc.

7. Melt blown technology


Melt blown technology is also a polymer laid non-woven (Figure 5.).In this process a thermoplastic polymer is extruded through die and the web is directly formed from the molten polymer. Molten polymer and hot air are blown into the free air, the mixing of fibre and high speed air with the ambient air creates “form drag” movement forward and backward. Melt blown fibres typically do not have regular diameter. The blown webs are consolidated by a combination of cohesive sticking and entanglement. Most widely used polymers are polypropylene, polyester, polyamide and polyethylene. Key parameter’s influencing melt blown technology are melt temperature of polymer, through put rate, air temperature and die to collector distance. Applications of melt blown non-woven include gradient filtration, due to the fibres small diameter and large surface area, good wicking and barrier properties, disposable products, surgical masks etc.

FIGURE 5. Melt blowing process


Spun bond and melt blown technologies:

  •  Capital investment on spun bond technology is higher than melt blown technology.
  •  Melt blown technology requires fibre forming polymers with lower melt viscosity unlike spun bond technology.
  • Melt blown technologies consume more energy than spun bond technology
  1. Web Drafting

One of the major short coming of a carded web is the difference in strength in the transverse and longitudinal direction. Hence, in order to improve the strength in the desired direction, depending on the type of laying, the carded webs are given the draft. The drafting reorient the web fibres and the number of fibres in the direction of the draft and improves the web quality.


Further, at times heavier webs are manufactured during laying which are made finer during the web drafting process. While drafting care should be taken to prevent width wise shrinkage of the web.

  1. Conclusions

In this module on non-woven, we have tried to brief on the scope of non-woven industry and their future growth prospects. Further, we have outlined the different definitions put forward by nonwoven organizations and associations. In the latter part of the module we have deliberated on the fibre preparation, web laying process and the web formation methods for both staple fibre and continuous filament fibres along with a few examples of their potential areas of applications.

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