what is nonwoven

[fahmidasiddiqa]

Nonwovens are webs made up of fibres. These webs have to be bonded. Bonding methods can be chemical, thermal or mechanical. The development taken place in nonwovens sector includes use of different materials for nonwoven includes Lyocel nonwovens, cellulosic nonwovens, and biodegradable nonwoven.

The development has also taken place in the process of manufacturing a nonwoven such as spun bonding and spun lacing, air laying, cross lapped nonwovens, forming random nonwoven webs with the static method, and needle loom for nonwoven. Due to the continuous research, newer nonwoven products started developing such as ecofriendly nonwoven products by solubalisation of viscose, production of nonwovens fibre board panel and latex foam sheet using coir and polypropylene blend, needle punched nonwovens blankets, etc. The vertical and horizontal types of nonwoven products have also been started for utilising in medical textiles.

Fibres used in manufacturing of nonwovens for medical applications

    Cotton

    Polyester

    Polypropylene

    Viscose glass fibre

    Wood fluff

    Polyamide

    Chitin

    Layocell

[fahmidasiddiqa]

 New development in biodegradable nonwovens

Over the last 30 years the nonwovens industry fibre usage has not only grown by a factor of ten. The fibres used have changed from almost exclusively biodegradable to most exclusively non-biodegradable despite concern for the environment among consumers becoming progressively stronger. In fact in the largest and most potentially, environmentally-sensitive market, cover stock for disposal diapers, and biodegradable products are non-existent. An expressed consumer preference for "environmentally friendly" products, in the disposables area at least, appears to meet an unmet need.

[fahmidasiddiqa]

Needle punched nonwoven blankets

Traditionally woven blankets where used in the Far East and Middle East countries. These methods are not economical and for that purpose a special technique has been developed known as needle punching. This process consists of three main stages:

    Predatory process

    Web formation

    Needling the fibres web
It is observed the thermal insulation value increases with increase in the nonwoven bulk density and needling density. Air permeability value reduces as there is increase in the nonwoven bulk density.

[fahmidasiddiqa]

Forming a random nonwoven webs with the static method

This development has taken place for random fibre arrangements of the roller card in nonwoven processed by different voltages and electro panel shapes. In this development it has been found that by changing shape of electrode panel can provide better random effects when the same voltage is used. The research indicates that the best panel shape is the circular holes and is positioned between the cylinder and doffer. The optimum random effect is obtained when original panel is electrified to 2kv between cylinder and doffer, or the panel with the circular holes is electrified with 20kv and placed over conveyor belts.

This process becomes very useful: 
i) To maintain the uniformity of web
ii) Iin manufacturing hybrid and composite products, which are used for implantation purpose effectively.

[fahmidasiddiqa]

Wet-laid nonwovens
i) "Borrowed" technology from the paper industry
ii)Fibres: 0.3 mm – 25 mm & 6.0 dtex max
iii)Fibres are dispersed and suspended in water at 0.05 % concentration

[fahmidasiddiqa]

Cross-lapped nonwovens

Cross-lapped nonwoven differs in many ways from other production process for nonwovens and the biggest advantage of this development is the flexibility regarding product and weight. Here the delivery belt is doubled, ie, batt of several layers are being formed; the card web enters the lappers with constant speed; the layering carriage has to perform an oscillating movement, as the layering carriage reduces its speed during reversal and is slowed down to zero so that it leads to accumulation of fibres in that area.

[fahmidasiddiqa]

Needle loom for nonwoven 

In recent years development has taken place for manufacturing all types of needle loom of nonwoven having the following advantages-
  I) The linger needle path results in better fibre orientation and fibre entanglement than the conventional needle machine
II) Superior web properties can be obtained with fewer needle preparation
III)It greatly enhances the construction of composites and hybrid products which are very useful for medical applications.

[naser.te]

A good post.

[smriti.te]

 :)