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Transcript of nonwovens
felts Definition and Classification of Nonwovens POLYMER-LAID
FORMATION Thank you for listening.. Production Process Drylaid nonwovens:
in drylaid web formation, fibres are carded(including carded and cross lapping) or aerodynamically formed(airlaid) and then bonded by mechanical, chemical or thermal methods.
Paper-like nonwoven fabrics are manufactured with machinery designed to manipulate short fibres suspended in liquid and are referred to as wet laid.
Polymer laid nonwovens:
or Spunmelt. In basic spunbonding system, sheets of synthetic filaments are extruded from molten polymer onto a moving conveyor as a randomly oriented web in the closest approximation to a continuous polymer to fabric operation.
In all nonwoven web formation processes, fibres or filaments are either deposited onto a forming surface to form a web or are condensed into a web and fed to a conveyor surface. Web formation involves converting staple fibres or filaments into a two dimensional web or three dimensional web assembly, which is the precursor for the final fabric. Dry-laid
Formation NONWOVENS OUTLİNE 1. Definition and Classification of nonwovens
2. Production Process
3. Dry-laid web formation
4. Polymer-laid web formation Nonwoven fabrics are broadly defined 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. What is Nonwoven Fabric? INDA Definition INDA describes nonwoven fabrics as ' sheet or web structures bonded together by entangling fibres or filaments, by various mechanical, thermal and/or chemical processes. These are directly made separate fibers or from molten plastic or plastic film.' EDANA Definition EDANA defines a nonwoven as 'a manufactured sheet, web or batt of directionally or randomly orientated fibres, bonded by friction, and/or cohesion and/or adhesion.' The most common products with nonwovens listed by INDA include: disposable nappies
sanitary napkins and tampons
sterile wraps, caps, gowns, masks and curtains used in the medical field
house hold and personal wipes
laundry aids (fabric dryer-sheets)
carpeting and upholstery fabrics, padding and backing
agricultural coverings and seed strips
automotive headliners and upholstery
civil engineering fabrics/geotextiles. European-produced nonwoven deliveries by end use: classification %of total hygiene 33.1
wipes, personal car 8.1
wipes, other 6.7
shoe leathergoods 1.9
coating substrates 2.4
liquid filtration 3.7
air/gas filtration 2.4
Civil engineering/underground 5.4
others/unidentified 5.3 WEB FORMING
FABRIC FINISHING Web forming methods
Elektrostatic laid Wet laid(of staple fibers)
Elektrostatic Spun Chemical Bonding:
Dispersion bonded by
Polymer solutions bonded Thermal bonding by
Infrared Finishing Methods:
Special Finished... These methods are:
chemical bonding. Raw Materials:
Polypropylene 63 %
viscose rayon 8%
other specialty fibres 3% Firdevs Fulden BUDAK Prepared by: Introduction: The dry laid nonwoven sector utilises carding, garnetting, airlaying and in certain specialist applications, direct feed batt formation processess to convert staple fibres into a web or batt structure that is uniform in weight per unit area. 1.Selection of raw materials for carding: Man-made fibres account of the majority of raw materials used in the nonwoven industry, and in the carding sector, polyester is the most widely used.
Polypropylene is also important, particularly in the manufacture of heavyweight needled fabrics for durableproducts such as floorcoverings and geosynthetics as well as needlepunched filtration media and lightweight thermal bonded fabrics for hygiene disposables.
Viscose rayon is extensively used in the medical and hygiene sectors, principally because of its high moisture regain.
Natural fibres such as cotton and wool have been carded as long as cards have been existence, man made fibres such as polyester have envolved to improve compatibility with high-speed nonwoven carding system. 2. Opening of fibres: Bale Breakers
Disc opener 3. Mixing and Blending: Multi-hopper systems
Fibre lubrication and spray systems
The influence of moisture content
Blending hoppers and self emptying bins
Cleaning systems 4.Carding:
Parallel- laid webs which in the fibres are preferentially oriented in the machine direction are produced directly from carding and related process.
The purpose of carding is to disentangle and mix fibres to form a homogeneous web of uniform weight per unit area.
Essentially, the principles of carding can be largely explained in just to basic actions. 'working' and 'stripping' 5. Cross-lapping: A cross-lapper is a continuous web transfer machine that normally follows a card or Garnett machine as part of an integrated web formation system.
Melt Blowing (MB) is a process for producing fibrous webs or articles directly from polymers or resins using high-velocity air or another appropriate force to attenuate the filaments.
Melt Blowing microfibers generally have diameters in the range of 2 to 4 µm, although they may be as small as 0.1 µm and as large as 10 to 15 µm.
Differences between MB nonwoven fabrics and other nonwoven fabrics, such as degree of softness, cover or opacity, and porosity can generally be traced to differences in filament size.
PROCESSING: The most commonly accepted and current definition for the MB 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 fiberous and self-bonding web.
Polymers for meltblowing: Polypropylene is easy to process and makes good web. Polypropylene with its low viscosity has a low melting point and is easy to draw into fibers.
Polyethylene is more difficult to melt-blow into fine fibrous webs than is polypropylene. Polyethylene is difficult to draw because of its melt elasticity.
Polybutylene terepthalate(PBT) processes easily and produces very soft, fine-fibered webs.
Nylon 6 is easy to process and makes good webs.
Nylon 11 melt-blows well into webs that have very unusual leather like feel.
Polycarbonate produces very soft-fiber webs.
Polystyrene produces an extremely soft, fluffy material with essentially no shot defects. Applications:
room air filter and recirculation
precious metal filtration and recovery
food and beverage filtration
surgical mask, respiratory filtration and healtcare products.
water and liquid filtration.
Absorption Electrospinning systems:
In the electrospinning process, the tensile force is generated by the interaction of an applied electric field with the electirical charge carried by the jet rather then the spindles and reels used in the conventional spinning process.
The jet emerges from the charged surface in the base region , and then electrical forces accelerate the polymer liquid and stretch the jet.