05-10-2012, 04:02 PM
Nonwovens as Medical Textiles
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Introduction
The use of nonwovens in medical arena goes back to the time of Second World War when need for new and large volumes of medical product had arisen. In several reports published, nonwovens were regarded as the most effective materials for bacterial barriers. Nonwovens give a performance much better than wovens in terms of cost, effectiveness, disposability etc. In hospitals, cross-contamination is always one of the biggest problems which were attributed largely to re-using of woven gowns, masks and other similar articles which would get contaminated and spread the germs. Nonwovens are more cost effective alternative which are disposable and reduced the problem of cross-contamination greatly.
Why nonwoven for medical products?
The properties which make nonwovens the best choice for medical products are:
Excellent barrier properties
Superior efficiency
Better performance (comfort, porosity, thickness and weight, water vapor transmission, air permeability etc.)
Increased protection for user (better physical properties like tensile, tear resistance, abrasion resistance etc.)
Easy to sterlize.
Economical manufacturing process.
Manufacturing Process
Various techniques are used for manufacturing of nonwovens but some of the techniques that are used specially for the Medical applications point of view are as follows:
Spun bonding
Spunlacing
Meltblowing
Needle punching
Wet laid
Dry laid
Spunlacing
Spunlacing/ Hydroentangling fabrics have specific properties as soft handle and drapability. Spunlacing uses high-speed jets of water to strike a web so that the fibres knot about one another. Spunlaced web is used to make surgical gowns and drapes, operation cover sheets, bed sheets, towels, etc. The steps of manufacturing spunlace fabric are:
Precursor web formation.
Web entanglement.
Water circulation.
Web drying.
The characteristics of the spunlace web are:-
Less destruction of fibres/or filaments, therefore, high strength can be achieved at reduced level of fibre cost.
No reinforced point, hence, it is soft, absorbent and permeable.
Binders are not used for bonding and so the process is environment friendly.
High production (approx. 300 m/min.).
It can condense and bond several layers.
Meltblowing
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. The web formed has degree of softness, cover or opacity and porosity.
Wet laid
Web produced by wet laying method is flexible and having strength. There are three characteristic stages in the manufacture of nonwoven bonded fabrics by the wet-laid method:
Swelling and dispersion of the fiber in water.; transport of the suspension on a continuous traveling screen
Continuous web formation on the
screen as a result of filtration
Drying and bonding of the web
Post processes
Post process for medical nonwovens is to give the product a suitable finish for its specific end use. The different types of finishes used in medical nonwovens are:
Soil Release Agents: For bed linens, gowns and apparel which are designed for multiple usages. May also be used on curtains, blankets etc.
Softeners: To make the webs feel soft against the skin. May be used for disposable pillows, bed sheets etc.
Water repellents: Used for bed sheets for kids, barrier apparel etc.
Flame Retardant Finishes: Used for bed linens, curtains, apparel, lab coats etc.
Antibacterial Finish: Very commonly applied to gauzes, dressings and sutures. The most popular one is silver nanocrystal finish.
Resin and Hand Builders: Used for apparel, gowns, bed linens etc.
Conclusion
Medical textile market is totally saturated with nonwoven products today. Nonwovens, because of their easily modifiable properties and excellent performance have become indispensable in this field. Medical and Hygiene sectors combined together consume more than 90% of the total nonwoven production in US. On the other hand, in developing countries of Asia, Africa and South America, demand for medical nonwoven is increasing significantly as a result of a fast-growing, increasingly urbanized, young, health-conscious population. In future, the demand of nonwovens in medical field is expected to grow steadily.