**7. Batt production by carding machines**

The main objective of carding process is individualization of fibers after removing short fibers up to some extent but the carding machines for nonwoven batt production have some modifications like two cylinders in place of one in conventional cards. In case of nonwoven engineered fabric production carding process is nearly final process because after carding the chances of fiber blending goes to zero. Generally short-staple revolving flat cards are most suitable for nonwoven industry due to its high opening potential with high production rate. These cards are equipped with autoleveller facility to improve the uniformity in mass per unit length of web. The card web has very low web density and high degree of variation in mass per unit length which is not suitable to be used directly in a nonwoven. There are three main way to lay the web during batt formation: parallel laying, cross laying and bias laying [32].

#### **7.1. Parallel laying**

The parallel laying is the basic, cheapest and simplest way of batt formation. In this system numbers of cards are situated one above another or side by side slightly above the main conveyor belt. The webs from each card came down onto the batt forming conveyor lattice with number of times (number equals to the card numbers) the mass per unit area. The card webs are turned through a right angle with the help of a guide which turns the web at 45°. These techniques provide maximum number of fiber lying along the batt direction which is called machine direction and very few remains across the batt direction. This type of web can be converted to engineered nonwoven fabric by opting anyone way of either bonding or entanglement. The strength of bond in parallel laid nonwoven remains less than individual fiber strength. The parallel laying process suits to manufacture narrow tapes and medical textiles while cross laying suits to filter and wipe fabrics. However randomized doffer cards neutralize the situation up to major extent by distributing the fibers randomly together with 'scrambling rollers'. Both parallel laid and cross laid laying shows anisotropic behavior, however by combining both parallel laying and cross laying isotropic nonwoven structures are engineered.

The final width of nonwoven engineered structure is a challenge and it can be overcome by combining various laying techniques [32].

#### **7.2. Cross laying**

weft yarn from the pirn on shuttle looms only or cones on shuttles looms. Most of the single phase weaving machines uses same kind of motions and an almost horizontal warp sheet between the back rest and the front rest. Such kind of system is utilized in common shuttle

It is difficult to define the nonwoven fabrics because country wise definitions of nonwoven are available which have very poor coherence with other. However the most acceptable definition was coined by the American Society for Testing Materials (ASTM D 1117-80). Although this definition solved the limited purposes to define the nonwoven. The nonwoven fabrics can be redefine as "A nonwoven textile structure can be produced by bonding, interlocking, intermingling, pressing of textile fibers or in combination by means of mechanical, chemical or thermal techniques and their combinations by shortening of conventional fabric manufacturing processes" . The nonwoven fabric manufacturing can be divided into two sections. The first section is dedicated for fiber web manufacturing and second section for bonding or interlocking of constituent fibers, the layering of various webs one over another in various fashions which decides the nonwoven structure properties up to major extent is called batt. The batt is subjected to bonding or interlocking process for final product manufacturing [31].

The main objective of carding process is individualization of fibers after removing short fibers up to some extent but the carding machines for nonwoven batt production have some modifications like two cylinders in place of one in conventional cards. In case of nonwoven engineered fabric production carding process is nearly final process because after carding the chances of fiber blending goes to zero. Generally short-staple revolving flat cards are most suitable for nonwoven industry due to its high opening potential with high production rate. These cards are equipped with autoleveller facility to improve the uniformity in mass per unit length of web. The card web has very low web density and high degree of variation in mass per unit length which is not suitable to be used directly in a nonwoven. There are three main way to lay the web during batt formation: parallel laying, cross laying and bias laying [32].

The parallel laying is the basic, cheapest and simplest way of batt formation. In this system numbers of cards are situated one above another or side by side slightly above the main conveyor belt. The webs from each card came down onto the batt forming conveyor lattice with number of times (number equals to the card numbers) the mass per unit area. The card webs are turned through a right angle with the help of a guide which turns the web at 45°. These techniques provide maximum number of fiber lying along the batt direction which is called machine direction and very few remains across the batt direction. This type of web can be

looms, rapier looms, projectile looms, air jet looms and water jet looms [30].

**6. Engineered fabrics by nonwoven fabric manufacturing**

**7. Batt production by carding machines**

**7.1. Parallel laying**

8 Engineered Fabrics

In order to result cross laying of webs to form batt, the cards are kept at right angles to the main conveyor lattice M and the card web is moved backwards and forwards across the main moving conveyor lattice.

The speed of main conveyor lattice is kept slow to accommodate many layers of card web in desired order. The cross laying systems suffers with two major problems; first, this system prone to form heavier batt at the edge due to overlapping. This issue can be solved by moving the of direction of batt at the edge of lattice. The second is to match the input speed of cross laying with card web speed. Generally input speed remains less and card web speed must reduce to match with input speed.

#### **7.3. Wet laying**

This technique of batt formation is influenced by paper making industry. The fibers are dispersed into water and water content is kept sufficient to prevent fiber aggregation. This system promotes the blending of fibers and laying them successfully. Wood pulps can also be blended with fibers to form the batt. This system is suitable to the batt of wooden pulp and fibers used in sanitary napkin manufacturing. The wet-laid batt is used in some other disposable engineered products like drapes, gowns, sometimes as sheets, as one-use filters, and as coverstock in disposable nappies [33].

## **7.4. Spun laying**

This technique of batt formation offers shortest route. This includes extrusion of the filaments from extruder, drawing the filaments and laying them in the form of batt. At the same time bonding also takes place which makes this process very economic from polymer to fabric manufacturing cost point of view. Initially, this process was developed for large scale production but at present small size machines are available to cater the need of small scale manufacturers. Initially polyester and polypropylene fibers were spun-laid but presently polyamide and polyethylene fibers can also be processed on this system. The microfiber technology also integrated with this system which enhanced the versatility to produce finer, softer and better filtration engineered fabric structures. The process starts from feeding of polymer chips into extruder which feeds the molten mass of polymer to a metering pump and then to a group of spinnerets which quenched further for quick solidification. The drawing process is assisted by hot air blowing in this system. The fiber orientation is controlled by both the direction of filament delivery tube and conveyor belt to assure uniform distribution of fibers [34].

region. Finally, the treated batt is cured at higher temperature to develop crosslinks both

Introductory Chapter: Engineered Fabrics http://dx.doi.org/10.5772/intechopen.82717 11

This technique of bonding is tagged as eco-friendly because the application of any kind of chemical is negligible. Productivity of thermal bonding process remains higher than any other chemical bonding process. Thermal bonding process is energy efficient also because it saves the energy which consumes to evaporate water from the binder and curing. Thermal bonding strategy can be divided into three classes like in first all of the fibers of same type with common melting behavior, second; a blend of fusible (lower melting point) and nonfusible (either the higher melting point or non-melting fibers) fibers and third; by application of bi-component fiber in which one component is fusible and other component is non-fusible. The temperature is applied at a localized area with or without pressure to melt the fusible

In this technique latex binder is sprayed which act as bonding element to bind the fibers. There may be more number of spray cycles depending upon desired bonding extent and batt thickness because every spray cycle reduces the batt thickness up to some extent. These engineered fabrics can be used as raw material for hometech sector as quilt filling material,

In order to reduce the application of water in various bonding techniques which not only enhances the cost of manufacturing due to essential drying but also the risk of binder migration, the foam bonding is better alternate in this direction. A definite amount of compressed air is passed through binder solution to create foam and then it applied on both side of batt with the help of horizontal nip of the impregnating roller. Foam consist limited amount of binder and negligible water content which suits for targeted application for bonding point

This technique is used to apply the binder on one or both side of batt to limited portion and in a set pattern. In order to assure penetration of binder well inside the batt, it is first impregnated with water and then binder is printed on batt in defined pattern either a printing roller or a rotary screen printer. The ratio of printed/unprinted area decides the ultimate properties of final nonwoven engineered fabric. The limited application of binder in print bonded fabric keeps fabric soft and pleasant feel. Print pattern and print content decides on the basis of type of fiber, fiber orientation and other properties of fibers used in the batt. Print-bonded fabrics have found its application in disposable/protective clothing, coverstock and wiping cloths.

inside and between the polymer particles at 120–140°C for 2–4 min.

fiber component and to stick with non-fusible fibers [38].

duvets and some typical type of filters [39].

**7.8. Thermal bonding**

**7.9. Spray bonding**

**7.10. Foam bonding**

**7.11. Print bonding**

of view.

#### **7.5. Air laying**

The air-laying system is capable to offer the desired batt in single stroke at high speed without first making lighter weight web and then by laying. The fiber opening potential of this system is limited and needs ample pre-opening before feed to air laying system. This system consist opening and blending section in back of feed hopper which is used to deliver fiber sheet to the feed rollers. The fibers are then taking-off by consist fine wire metallic clothing on its surface, revolves at high speed. Some optional stripping rollers may attach to enhance the opening potential of the system. The opened fibers are removed by powerful air stream from opening cylinder surface. The air stream carries the fibers to cage like conveyor lattice to form the final batt [35].

#### **7.6. Melt blown**

The melt blowing process is another very promising method of manufacturing very fine deniers. This system produces fibers without the use of fine orifice spinnerets at high production rate. In this arrangement polymer is melted and extruded normally as other melt extrusion processes but through relatively large spinneret orifices. After complete melting, filtration, polymer melt extrude out from spinneret orifices it directly comes in the contact of very high temperature (above the melting temperature of polymer, Tm) hot air stream which assist in filament stretching up to maximum extent. The staple fibers of very fine deniers produced in this way are collected on the surface of permeable conveyor to form a batt as in air laying and spun laying.

Bonding is rarely required here and in most of the cases the melt-blown batt is laminated on another nonwoven structure (may be a spun-laid or the melt-blown batt). This type of laminated engineered fabric is used to engineer breathable protective clothing for use in agriculture hospitals and industry. These structures are useful as battery separators, industrial wipes and clothing interlinings with good insulation properties also. If melt blown layered structure is not bonded and directly collected as nonwoven batt then it is used as ultrafine filters for air conditioning and personal face masks, oil-spill absorbents and personal hygiene products. This technique is growing with 10% annual growth rate [36].

#### **7.7. Chemical bonding**

Chemical bonding is the process of sticking fibers of batt by treating/modifying either a specific area of batt or whole batt. A variety of bonding agents/adhesives are available in which acrylic latex, styrene butadiene lattices and vinyl acetate latex are the major one. The bonding agent must have ample wettability otherwise it can be maintained by adding appropriate amount of surfactants [37]. After judicious application of bonding agent, the batt is dried then to remove aqueous component and making proper bonding among the fibers of that localized region. Finally, the treated batt is cured at higher temperature to develop crosslinks both inside and between the polymer particles at 120–140°C for 2–4 min.

#### **7.8. Thermal bonding**

spinnerets which quenched further for quick solidification. The drawing process is assisted by hot air blowing in this system. The fiber orientation is controlled by both the direction of

The air-laying system is capable to offer the desired batt in single stroke at high speed without first making lighter weight web and then by laying. The fiber opening potential of this system is limited and needs ample pre-opening before feed to air laying system. This system consist opening and blending section in back of feed hopper which is used to deliver fiber sheet to the feed rollers. The fibers are then taking-off by consist fine wire metallic clothing on its surface, revolves at high speed. Some optional stripping rollers may attach to enhance the opening potential of the system. The opened fibers are removed by powerful air stream from opening cylinder surface.

The melt blowing process is another very promising method of manufacturing very fine deniers. This system produces fibers without the use of fine orifice spinnerets at high production rate. In this arrangement polymer is melted and extruded normally as other melt extrusion processes but through relatively large spinneret orifices. After complete melting, filtration, polymer melt extrude out from spinneret orifices it directly comes in the contact of very high temperature (above the melting temperature of polymer, Tm) hot air stream which assist in filament stretching up to maximum extent. The staple fibers of very fine deniers produced in this way are collected on the surface of permeable conveyor to form a batt as in

Bonding is rarely required here and in most of the cases the melt-blown batt is laminated on another nonwoven structure (may be a spun-laid or the melt-blown batt). This type of laminated engineered fabric is used to engineer breathable protective clothing for use in agriculture hospitals and industry. These structures are useful as battery separators, industrial wipes and clothing interlinings with good insulation properties also. If melt blown layered structure is not bonded and directly collected as nonwoven batt then it is used as ultrafine filters for air conditioning and personal face masks, oil-spill absorbents and personal hygiene

Chemical bonding is the process of sticking fibers of batt by treating/modifying either a specific area of batt or whole batt. A variety of bonding agents/adhesives are available in which acrylic latex, styrene butadiene lattices and vinyl acetate latex are the major one. The bonding agent must have ample wettability otherwise it can be maintained by adding appropriate amount of surfactants [37]. After judicious application of bonding agent, the batt is dried then to remove aqueous component and making proper bonding among the fibers of that localized

products. This technique is growing with 10% annual growth rate [36].

filament delivery tube and conveyor belt to assure uniform distribution of fibers [34].

The air stream carries the fibers to cage like conveyor lattice to form the final batt [35].

**7.5. Air laying**

10 Engineered Fabrics

**7.6. Melt blown**

air laying and spun laying.

**7.7. Chemical bonding**

This technique of bonding is tagged as eco-friendly because the application of any kind of chemical is negligible. Productivity of thermal bonding process remains higher than any other chemical bonding process. Thermal bonding process is energy efficient also because it saves the energy which consumes to evaporate water from the binder and curing. Thermal bonding strategy can be divided into three classes like in first all of the fibers of same type with common melting behavior, second; a blend of fusible (lower melting point) and nonfusible (either the higher melting point or non-melting fibers) fibers and third; by application of bi-component fiber in which one component is fusible and other component is non-fusible. The temperature is applied at a localized area with or without pressure to melt the fusible fiber component and to stick with non-fusible fibers [38].

#### **7.9. Spray bonding**

In this technique latex binder is sprayed which act as bonding element to bind the fibers. There may be more number of spray cycles depending upon desired bonding extent and batt thickness because every spray cycle reduces the batt thickness up to some extent. These engineered fabrics can be used as raw material for hometech sector as quilt filling material, duvets and some typical type of filters [39].

#### **7.10. Foam bonding**

In order to reduce the application of water in various bonding techniques which not only enhances the cost of manufacturing due to essential drying but also the risk of binder migration, the foam bonding is better alternate in this direction. A definite amount of compressed air is passed through binder solution to create foam and then it applied on both side of batt with the help of horizontal nip of the impregnating roller. Foam consist limited amount of binder and negligible water content which suits for targeted application for bonding point of view.

#### **7.11. Print bonding**

This technique is used to apply the binder on one or both side of batt to limited portion and in a set pattern. In order to assure penetration of binder well inside the batt, it is first impregnated with water and then binder is printed on batt in defined pattern either a printing roller or a rotary screen printer. The ratio of printed/unprinted area decides the ultimate properties of final nonwoven engineered fabric. The limited application of binder in print bonded fabric keeps fabric soft and pleasant feel. Print pattern and print content decides on the basis of type of fiber, fiber orientation and other properties of fibers used in the batt. Print-bonded fabrics have found its application in disposable/protective clothing, coverstock and wiping cloths.

#### **7.12. Powder bonding**

Powder bonding technique is based on the application of thermoplastic powders alternate to thermoplastic fibers. Rest processes remain similar to thermobonding. The powder bonded engineered fabrics show better flexibility and softness with poor bonding strength. These structures are used in protective apparel and coverstock areas where high bulk is desired.

**9.1. Rapier looms for engineered fabrics manufacturing**

system weft is inserted alternately from both sides of the machine [43].

insertion rates have increased remarkably.

**9.2. Projectile looms**

Rapier was the first concept that successfully replaced the shuttle weft insertion system. First generation of Rapier looms did not get commercial acceptance due to its very low speed. With the invention and introduction of precision engineering and microprocessor controls, the weft

The Rapier loom of 2.5 m width has close competition with projectile loom. The single rapier looms are rigid rapier slow speed looms. However, the invention of double rapier has increased the commercial acceptability because wide variety of threads can be processed on these looms. Both rapier enter from both extreme end of reed and meet at the middle of cloth width to transfer the weft thread from one rapier to other rapier. Rapier looms have two weft insertion systems; one is Gabler and other is Dewas system. In case of Gabler weft insertion

The weft thread is cut every second pick with hairpin selvedges being formed alternately on both selvedges but weft is inserted from one end of rapier loom in Dewas system. Dewas system is dominating now a days and most of the looms has weft feeding system on one side. Double rapier weaving machines may have either the rigid or flexible rapiers. Dornier HTV and P19 series Rapier looms are capable of weaving most of the industrial fabrics with weft linear densities of up to 3000

looms are used widely to manufacture wide range of engineered fabrics starts from opencoated geotextile mesh, heavy conveyor belt cloths, home textiles, and canvas and furnishing items. Rapier looms are most suitable weaving machines to carry and run Jacquard shedding device.

The first projectile weaving machine was based on single projectile which had provision to strike the projectile from each side of the loom. This machine had weft supply system from both side of the loom. The latest projectile looms have multiple projectiles which are stroked from one side and are returned back to the picking position with the help of a conveyor belt. The contribution of Sulzer Textile to develop projectile loom and enhanced its versatility in terms of improved weft insertion rates, machine efficiency and extended the range of fabrics manufactured is unforgettable. Projectile loom offers facility to use a winding cone directly without rewinding which saves cost and time both. The length of standard projectile is 90 mm with 40 g weight. The weft thread is withdrawn from weft supply cone through a weft brake and a weft tensioning device to the weft feeder which places it into the gripper of the projectile [44].

A torsion rod system is used for picking which transfers the maximum possible strain-energy to the projectile before it leaves the picker shoe. The strain energy can be adjusted by changing the position of torsion bar. Sulzer Textil redesigned the reed of projectile loom which offer

3600 mm reed width machine. Latest projectile looms are capable to insert six color weft threads, fancy threads and wide variety of material from fine polyester to coarse woolen threads successfully. The machines can be equipped with a variety of shedding mechanism like dobby and jacquard. Machine performance can be monitored with microprocessors. Sulzer Ruti and Jäger are two major manufactures of projectile loom. Jäger have developed a hydraulically propelled projectile loom. Projectile looms are capable to weave wide variety of engineered fabrics of up

more effective and strong beat-up. A weft insertion speed of 1300 m min−<sup>1</sup>

. Rapier

Introductory Chapter: Engineered Fabrics http://dx.doi.org/10.5772/intechopen.82717 13

can be achieved on

tex, in loom widths of up to 4600 mm and at weft insertion rates of up to 1000 m min−<sup>1</sup>
