**3.3. Wetlaid nonwovens**

The fiber preparation is close to classical textile industry staple fiber preparation including bale opening, blending, coarse, and fine opening. Then the web forming machine is fed with the help of a chute in case of short staple fibers or with the help of a hopper in case of long staple fibers. The fibers fed by a chute or hopper condensed into the form of a lap are introduced into a carding machine. The carding machine separates fibers, starts the process of individu‐

The web is then formed into the desired web structure by layering the webs extracted from the carding machine. Based on the final chosen weight and web structure, the layering can be

Web strengthening can be done mechanically with the help of needle punching which consists in bonding nonwoven web by mechanically interlocking the fibers through the web using barbed needles (Figure 4), with the help of stitch bonding which consists in consolidating fiber webs using knitting elements or with the help of hydro-entanglement which consists in locking

completed by using longitudinal layering, cross layering, or perpendicular layering.

the fibers together using fine high pressure water jets directed across the web.

**Figure 4.** SEM photomicrograph of needle-punched nonwoven (natural and synthetic fibers)

the chemical binder to the web and curing it.

by thermal bonding.

Mechanical bonding can be replaced with web chemical bonding which consists in applying

In case of thermoplastic and thermostable fiber blend web, the strengthening can be achieved

alization, and delivers the fibers in the form of a web [24,25].

58 Non-woven Fabrics

This method relates to paper-based nonwoven fabrics which are manufactured by suspending short length fibers in water and pumping the suspension over a moving mesh in order to form a fibrous **web** [3].

Figure 5 is a schematic illustration of wetlaid technique. The blades of a very strong mixer transform fibers, wood pulp, and water to a perfect slurry suspension. Webformer deposes the suspension over the screen, and depending on the application of nonwoven, it will pass through a suitable bonding stage. Finally, nonwoven will be dried and wound up.

**Figure 5.** Wetlaid web formation [www.edana.org]

All fibers which are dispersible in fluids and do not dissolve can be transformed into a **web** form by using the wetlaid method. One of the main advantages of the wetlaid method is a very good product homogeneity due to the very good homogeneity of the **web**.
