Spunbonding Method for Nonwoven Fabric Production
B.J.Group, Mawna, Gazipur
Spunbonding is a one-step manufacturing process from either the chemical or polymer stage to the finished nonwoven products on a roll. The major steps in the spunbonding process are web formation, web bonding, and winding into rolls. Melted polymer is first fed into an extruder and forced through a spinneret; the fibres are then stretched after cooling. The web is made by continuously placing fibres to a depth slightly larger than the final product onto a moving conveyor belt. The fibres form loose web, which may be bonded together by one of three bonding techniques: mechanical bonding, thermal bonding, or chemical bonding.
In spunbonding process, fabrics are produced directly from a thermoplastic polymer such as polyester, nylon, polypropylene, or polyethylene. The molten polymer is extruded through a spinneret, cooled slightly in the air, and laid on a moving conveyor belt to form a continuous web. As the web cools, the fibers bond.
Spunbonding Method for Nonwoven Production
Spunbonding method is used for man-made filament fibers that melt under heat, such as polyester. Spunbond fabrics are produced by depositing extruded, spun filaments onto a collecting belt in a uniform random manner followed by bonding the fibers. Spunbond fabrics are characterized by tensile, tear, and burst strengths, elongation-to-break, weight, thickness, porosity and stability to heat and chemicals. Spunbond products are employed in carpet backing, geotextiles, and disposable medical/hygiene products. Since the fabric production is combined with fiber production, the process is generally more economical than when using staple fiber to make nonwoven fabrics.
The spunbonding sequence is shown in Figure-1. The melt, dry or wet extrusion spinning techniques can be adapted in a spunbonding process. However, melt spinning is the prominently used technique. The hopper feeds the polymer chips to an extruder where they are melted. The molten polymer is filtered and is extruded through the spinneret to form the filaments. Depending upon the fabric width, two or three spinnerets are laid side by side to increase the number of filaments. The extruded filaments are quenched by a stream of cold air and are subjected to either mechanically or pneumatically attenuation for orienting the molecules thereby increasing the strength.
The pattern of the spun-bonded fabric and arrangement of the fibers can be varied in several ways. The spinneret can be rotated to deliver filaments in different patterns and arrangements; a jet of air (a controlled stream of air) can be introduced to tangle the filaments; the conveyor can be moved at variable speeds to collect different quantities of filaments at selected locations; and applying an electrical charge to make the fibers loop and crimp.
Spunbonded fabrics are strong because of the filament fibres and are not easily torn. They are used for a wide variety of products ranging from apparel interlinings, carpet backing, furniture and bedding to bagging and packing material. Spunbonded fabrics may be used in geotextiles to control erosion or in constructing road. Some spunbonds made from olefins are used as a tough, especially durable substitute for paper in wallcoverings, charts, maps, tags and the like.
Fabrics made by this process include Mirafi 140, made from nylon and polypropylene; Celestra polypropylene; Reemay polyester; Tyvek polyethylene; Typar polypropylene; Bondtex polyester; Cerex nylon; and Bidim polyester.
Uses of Spunbonding Nonwovens:
- Coverings for bedding (for example mattress covers)
- Carpet underlay/backing
- Backings for wallcoverings
- Curtain header tapes/backing
- Upholstery (including synthetic leather)
- Furniture backings
- Cover stock for diapers and hygiene products
- Surgical materials
- Roof Materials and other construction material
- Industrial products
- Nonwovens: Process, structure, properties and applications by T. Karthik, R. Rathinamoorthy, C. Praba Karan
- Advances in Technical Nonwovens Edited by George Kellie
- Applications of nonwovens in technical textiles Edited by R. A. Chapman
- Understanding Textiles for a Merchandiser by Shah Alimujjaman Belal
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.