Introduction to nonwovens

Introduction to nonwovens

According to the American Society of Testing Materials (ASTM D 1117-80), nonwovens are defined as follows:

‘A nonwoven is a textile structure produced by the bonding or interlocking of fibers, or both accomplished by mechanical, chemical, thermal or solvent means and combinations thereof. The term does not include paper or fabrics that are woven, knitted or tufted.’ Nonwoven are still increasing in importance; production is increasing at the rate of 11% per annum.

One of the major advantages of nonwoven is that it is carried out swiftly directly from the raw material to the finished fabric generally however there are exceptions. Naturally, this leads to low labor cost as there is no role of material handling unlike other textile processes. All the nonwoven processes involve two stages, initially the fibers are prepared into a suitable form in order for them to bond. There are various different methods of processing a fiber, different processing exudes its own particular characteristic in the final fabric. There are number of different bonding methods which have notable effect on the finished fabric properties. Almost all the fiber processing methods can be combined with all bonding methods allowing wide range of final properties in the material.

In the fiber processing the very first step involves making a thin layer of fiber which is termed as a web. When several layers on web are placed on each other it forms a batt, which directly goes to the bonding. The first step pf nonwoven processing is normally called batt production.

Applications of nonwovens:

Nonwovens have variety of application which includes:

Nonwovens are used in diaper stocks, feminine hygiene products and other absorbent material. They are also used in carpet backing and in composites (marine sail laminates, table cover laminates). These days it is widely used in shopping bags as the society is heading toward a sustainable approach.

Medical application of nonwoven includes isolation gowns, surgical gowns, surgical masks. Nonwovens are also used filtration purpose like in pharmaceutical industry, mineral processing, vacuum bags.

In geotextiles; nonwoven geotextiles containers (sand bags) are used for soil stabilizers, frost protection for canal water bodies, land fill liners. Nonwovens are advantageous compared to that of woven, they are more robust than woven bags of the same thickness.

Nonwoven defects:

Real time monitoring and feedback- Fabric weight variations and coated fabric weights, moisture content, permeability and other properties.

Web faults- thick and thin areas, holes, contamination, various additional marks, process specific defects.