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Nonwovens for Home Textiles



Nowadays in home textiles nonwoven fabrics are mostly used as home furnishing fabrics.



By By Dr. R. Shanthi, Asst. Prof. (SRG), Department of Fashion Technology, Kumaraguru College of Technology & M. G. Iswariya, M.Tech, Apparel Technology & Management, Kumaraguru College of Technology



Published March 11, 2013
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Nonwovens for Home Textiles
Nonwovens For Home Textiles Roller towel made of nonwoven fabric with tear-off fibers isolated over blue.
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Nonwoven fabric is a fabric-like material made from lengthy fibers, bonded together by chemical, mechanical, heat or solvent treatment. In simple terms, they are textiles made from fibers or threads joined together without weaving. Nonwoven materials classically lack strength unless densified or toughened by a backing. In recent years, nonwovens have become an alternative to polyurethane foam.[1, 2]

Nowadays nonwoven fabrics are mostly used as home furnishing fabrics. Nonwoven fabrics are described as sheet or web structures bonded together by entangling fiber or filaments (and by perforating films) mechanically, thermally or chemically. They are flat, porous sheets that are made directly from separate fibers or from molten plastic or plastic film. They are not made by weaving or knitting and do not require converting the fibers to yarn. Typically, a certain percentage of recycled fabrics and oil-based materials are used in nonwoven fabrics. The percentage of recycled fabrics varies based upon the strength of material needed for the specific use. Conversely, some nonwoven fabrics can be recycled after use, given the proper treatment and facilities. For this reason, some consider nonwovens a more ecological fabric for certain applications, especially in fields and industries where disposable or single use products are important, such as hospitals, schools, nursing homes and luxury accommodations.

Nonwoven fabrics are engineered fabrics that may be a limited life, single-use fabric or a very durable fabric. Nonwoven fabrics provide specific functions such as absorbency, liquid repellence, resilience, stretch, softness, strength, flame retardancy, washability, cushioning, filtering, use as a bacterial barrier and sterility. These properties are often combined to create fabrics suited for specific jobs, while achieving a good balance between product life and cost. They can mimic the appearance, texture and strength of a woven fabric and can be as bulky as the thickest paddings. In combination with other materials they provide a spectrum of products with diverse properties and are used alone or as components of apparel, home furnishings, health care, engineering, industrial and consumer goods.[1]

Types of nonwoven fabrics: Nonwovens, depending on the production process can be divided into:

• Materials produced by physicochemical methods; and
• Mechanically produced materials.

Materials produced by physicochemical methods

Most nonwoven materials, are made by binding fibers with adhesives. The most common glued materials are those based on fibrous cloth (a layer of textile fibers whose weight is 10–1000 gsm and more). The cloth is most often formed mechanically from several layers of combed fibers passing through the dotting drum of a combing machine. Fibrous cloth may be produced by the aerodynamic method in which the fibers are removed from the drum of the combing machine by a stream of air and transferred to a mesh drum (condenser) or a horizontal mesh with a maximum speed of up to 100 m/min, or by water dispersion of the fibers on the mesh of a paper machine.[3]

A fibrous cloth is usually made of cotton, a mixture of viscose and polyamide fibers or the waste products of textile manufacture, including unspun fibers. The most common method of producing bonded nonwoven materials are to  impregnate  the cloth with a liquid adhesive or  spraying/printing the adhesive over the surface of the cloth. Gluing the fibers includes saturate bonding and spray bonding or a latex adhesive is applied to the fibers and then the fabric is dried. The impregnated material is dried and treated in chambers heated by hot air or infrared radiation. The nonwoven materials made in this fashion (at a rate of 50 m/min and more) are used as interlacing and sealing materials, as heat and sound insulation materials for upholstery, bedding and drapery liners.

Melting fibers together can only be accomplished with synthetic, thermoplastic fibers or with a blend of fibers containing thermoplastic fibers or fusable powders. These methods include thermal bonding (heat applied to the web with or without pressure) a carded web, ther-mobonding a spunlaid web with a calendar, thermobonding a melt blown or flash spun web with a calender, thermal bonding a carded or air laid high loft web in an oven.In the hot-pressing process, the fibers are bonded by thermoplastics such as polyamides, polyethylene, and polyvinyl chloride at pressures of up to 2 mega newtons per sq m (MN/m2), or 20 kilograms-force per sq cm (kgf/cm2), at high temperatures, usually on special calenders. The bonding is preceded by thermal treatment of the fiber layer, which contains an adhesive that is applied to the fibrous cloth during its formation or after its formation.

In the spunbonded method, synthetic fibers are formed as they leave the spinnerets of spinning machines and pass through troughs in which they are stretched in an air current; they are then placed on a conveyor belt and form a sheet. The material formed in this way is most often bonded with an adhesive; in some cases the stickiness of the fibers themselves is sufficient.[4-8]

Mechanically produced materials

Stitch bonded Nonwovens
According to the maliwatt technique in the German Democratic Republic [GDR] and the Arachne technique in Czechoslovakia, stitched nonwoven materials are made by joining  fibers into the fabric, which is moving through a knitting-stitching machine, stitching with threads placed and joined like foundation stitches on a knitting machine. Such nonwoven materials are used as thermal insulation or packing material or as the foundation in the manufacture of quilts, blankets and  jackets.

Thread-stitched nonwoven materials (Malimo materials; GDR) are made by stitching with one or more thread systems. They are used for decoration, for beach wear or for towels. Especially useful are thread-stitched materials with pile loops (half-loops), which can compete successfully with woven shag fabrics.  Sheet-stitched nonwoven materials are made by stitching a pile-woven textile sheet with napped yarn which facilitates improved structure and properties of the sheet. Foundations for tufted carpets (550 cm wide) are stitched with carpet yarn, using needles to pull it through the fabric. On the return motion of the needle, the worsted is caught on a hook, and a loop is made. To secure the loops, an adhesive is applied to the reverse of the carpet. Threadless nonwoven materials are made on knitting-stitching machines (Voltex material in the GDR and Arabeva in Czechoslovakia). Such materials may consist of fabric and cloth made of staple fibers. After the cloth fibers are pulled through the scrim, sturdy loops are formed on the reverse of the material, and a deep, fluffy pile is formed on the front. Such materials are used as thermal stuffing or linings for rugs and carpets and blankets. [9]

Mechanical interlocking
Mechanically interlocking includes spunlace (hydroentangled) and needlepunching. Spunlacing is a process[10,11] of entangling a web of loose fibers on a porous belt or moving perforated or patterned screen to form a sheet structure by subjecting the fibers to multiple rows of fine high-pressure jets of water.[12, 21]  The formed web  is first compacted and prewetted to eliminate air pockets and then water needled. Pressures as high as 2200 psi are used to direct the water jets onto the web. The impinging of the water jets on the web causes the entanglement of fibers. The jets exhaust most of the kinetic energy primarily in rearranging fibers within the web and, secondly, in rebounding against the substrates, dissipating energy to the fibers. A vacuum within the roll removes used water from the product, preventing flooding of the product and reduction in the effectiveness of the jets to move the fibers and cause entanglement.

The application of spunlace nonwovens includes kitchen and  bath  towels and wipes and also for bed linen as they are  eco-friendly, oil and water absorbent, bacteria proof with no smell and safe for sensitive skin.[13]

Melt blowing
The melt blowing process is a one-step process  in which high-velocity air blows a molten thermoplastic resin from an extruder die tip onto a conveyor or takeup screen to form a fine fibrous and self-bonding web. In other words it is a nonwoven web forming process that extrudes and draws molten polymer resins with heated, high velocity air to form fine filaments. The filaments are cooled and collected as a web onto a moving screen. In some ways the process is similar to the spunbond process, but meltblown fibers are much finer and generally measured in microns. Meltblowing is a spunlaid process. The term is also spelled “melt blowing.”[14,15]

Needlepunching
Needlepunched nonwovens are created by mechanically orienting and interlocking the fibers of a spunbonded or carded web. This mechanical interlocking is achieved with thousands of barbed felting needles repeatedly passing into and out of the web with the help of a needle loom. It is a kind of dry non woven, nonwoven fabrics of acupuncture is the use of the needle puncture effect, fluffy fiber net reinforcement into cloth.[16]

The needle loom is made up of needle board with thousands of needles is fitted into a needle beam which  passes up and down through two perforated plates—the bottom web plate moves the fabric and the top stripper plate which removes the fibers from the needles. The exit rolls wind the needlepunched fabric at the end of the loom. Four  types of nonwovens for mattresses namely medium soft, hard with plain surface, one side hard and one side soft and nonwoven poly pet are used as intermediate product by home furnishing manufacturers and mattress manufacturers.[17] They are also used as spring insulators that hold staples that fasten the upholstery to the wood frame, insulators in mattress construction to cover springs and as flanges are the panels of material that surrounds the edge of the mattress and join the mattress top and bottom together.[18]

Airlaid paper
Airlaid paper is a textile-like material categorized as a nonwoven fabric made from wood pulp. Unlike the normal papermaking process, air-laid paper does not use water as the carrying medium for the fibre. Fibres are carried and formed to the structure of paper by air.[1] The characteristics of airlaid paper nonwovens are outstanding absorbency for wipes and towels, multi-layered materials that gather dust, microbes, and other household irritants efficiently and economically, tabletop and table napkin with excellent printability, versatile fabrics for every task from dusting to heavy scrubbing, improved strength in wet or dry wiping, specialty fabrics available for pre-moistened wipes, low lint-gathering properties and embossed wipe surface for antimicrobial qualities. The applications include napkins and tablecloths, pre-moistened cleaning wipes, dry wipes, kitchen towels, vacuum cleaner bags and kitchen and fan filters.[19]

Engineered nonwoven fabrics

A major benefit of a nonwoven is the ease of engineering physical property requirements into the fabric that may be necessary for specific conversion operations or performance issues. Nonwovens that go into the home furnishing market are relatively easy for manufacturers to produce as opposed to more technical applications. Household furnishings must withstand  high wear and  tear, stains, spills and dirt which brings in the necessity of engineering nonwovens to ensure a longer lifespan. Thermal bonded spunlaid polyester nonwovens made from bicomponent filaments, with a polyester core and a polyamide skin, are  used as a primary backing in applications such as tiles and broadloom carpeting for dimensional stability. Spunbonded  nonwovens are ideal  for the furniture, bed coverings, spring insulation, quilting and cushioning markets. High loft needlepunch and spunbond technologies are used to produce indoor and outdoor bedding products, quilts, comforter tops and pads. High loft provides the bulk and resilience and needle punching the strength and stability to the products.[20]

• Heat and flame resistance: Engineered nonwoven fabrics can be designed to have an extremely high melting point as well as dimensional stability at high temperatures.
• Durability: Relative to their weight, engineered nonwoven fabrics can be designed to wear better than comparable weights of woven or knitted materials. When used as backing material, engineered nonwoven fabrics can increase the longevity of upholstery by reducing internal abrasion (up to five times more durable than other traditional materials).
• Anti- allergy and antimicrobial properties: Engineered nonwoven composites can be laminated to bedding and mattress materials to protect allergy sufferers from dust and mites - without any chemical additives.
• Strength and uniformity: Many engineered nonwoven fabrics have higher tensile, tear, and burst strength than their traditional textile counterparts and can resist repeated load bearing. Home furnishings can thus retain their form and appearance over longer periods of time, making them very cost-effective.
• Fluid resistance and retention: Engineered nonwoven fabrics can be designed to retain fluids and to resist staining. Engineered nonwoven fabrics can also be designed to resist attack by many solvents, alkalies, and other chemicals.[23]

Conclusion
Nonwovens are found in many household furnishing applications. Nonwovens lie in  many  hidden areas around the home, such as carpet underpaddings, drapery liners, ironing board pads, lamp shades, slipcovers, scrims, tickings and upholstery backings as well as in more obvious places including bed sheets, bed spreads, futons, draperies, mattress covers and pads, pillows, quilts and tablecloths. With so many areas of the home containing nonwoven material, manufacturers have a lot of room for experimentation.  The nonwovens industry will have to produce diverse specially engineered home textile products to the ever-changing consumer market.

REFERENCES:
[1] http://en.wikipedia.org/wiki/Nonwoven_fabric
[2] http://encyclopedia2.thefreedictionary.com/nonwoven+fabric
[3] DefVol2No14NonwovenFabric.pdf
[4] http://en.silepu.com/product/&FrontComContent_list01-1287456439621ContId=6a307a5b-a6d4-49ff-b572-b6747fa3d4df&comContentId=6a307a5b-a6d4-49ff-b572-b6747fa3d4df&comp_stats=comp-FrontComContent_list01-1287456439621.html
[5] http://www.fibre2fashion.com/industry-article/pdffiles/Spunbonded-Nonwovens.pdf
[6] www.hongwei.en.alibaba.com
[7] www.dongxiang-nonwoven.com
[8] Lim H.(2010),A review of Spun bond process, JTATM, 6, 1-12
[9] http://encyclopedia2.thefreedictionary.com/Nonwoven+Materials
[10] White, C. F.: Hydroentanglement Technology Applied to Wet Formed and Other Precursor Webs, TAPPI Nonwovens Conference, 1990, 177-187
[11] Drelich, A.: A Simplified Classification of Nonwoven Fabrics, Sixth Annual Nonwovens Conference, University of Tennessee, Knoxville, 1988
[12] Heeler J., Hydroentanglement of short fibers, TANDEC Conference November 2001
[13] http://jthd.en.alibaba.com/product/526815889-213067165/Spunlace_Nonwoven_Disposable_Kitchen_Towel.html
[14] http://www.inda.org/spunbond-melt-blown.html
[15] http://web.utk.edu/~mse/Textiles/Melt%20Blown%20Technology.htm
[16] http://www.aokok.cn/En/NewsDetail_31.html
[17]http://www.engr.utk.edu/mse/Textiles/Needle%20Punched%20Nonwovens.htm
[18] http://www.inda.org/enduses/homefurn/application.html
[19] http://www.glatfelter.com/products/airlaid_materials/home_care.aspx
[20] http://shows.nonwovens-industry.com/articles/2002/04/home-is-where-the-nonwoven-is
[21]http://www.textileworld.com/Articles/2008/August_2008/Nonwovens/Spunlaced_Or_Hydroentangled_Nonwovens.html
[22] www.non-wovenfabrics.com
[23] http://www.inda.org/enduses/homefurn/advantage.html