Manufacturing Processes For

Synthetic Fibers

About half of the textiles produced in the world are made from man-made fibers.

Despite questions of aesthetics and taste, there should continue to be a significant demand for synthetic fibers, in large part because these fibers can be “tailor-made” to provide specific properties that natural fibers cannot provide.

IntroductionIntroduction

When the filaments emerge from the holes in the spinneret, the liquid polymer is converted first to a rubbery state and then solidified. This process of extrusion and solidification of endless filaments is called Spinning.

Spinning

Classifying Synthetic Fiber Manufacturing Processes

Spinning

Melt Solution

In their initial state, the fiber-forming polymers are solids and therefore must be first converted into a fluid state for extrusion. This is usually achieved by melting, if the polymers are thermoplastic synthetics (i.e., they soften and melt when heated), or by dissolving them in a suitable solvent if they are non-thermoplastic cellulosics.

Melt spinning is the preferred method for polymeric fibers.

Melt Spinning is simple and highly productive method.

Low-speed winder (up to 2500 m/min)

High-speed winder (up to 6000 m/min)

Melt Spinning

Nylon, Polyester

Olefin, Sulfar

Wet spinning is the oldest and the most complex process.

The spinnerets are submerged in a chemical bath and as the filaments emerge they precipitate from solution and solidify.

It is a low speed (150 m/min) process hence to increase the productivity Spinneret holes are increased.

Wet Spinning

Acrylics, Rayon

Spandex, Aramids

Dry Spinning is also used for fiber-forming substances in solution.

However, instead of precipitating the polymer by dilution or chemical reaction, solidification is achieved by evaporating the solvent in a stream of air or inert gas.

Dry Spinning

Acetate, Triacetate

Acrylics, Vinyon

Melter

Metering Pump

Filter

Spinneret

Quench

Finish Applicator

Parts Of Melt Spinning Machine

Solution Vessel

Feed Vessel

Heat Exchanger

Metering Pump

Filter

Spinneret

Spin Bath(Wet), Spin Cabinet(Dry)

Winding

Parts of Wet and Dry Spinning Machine

The spinnerets used in the production of most manufactured fibers are similar, in principle, to a bathroom shower head.

Spinneret may have from one to several hundred holes.

The tiny openings are very sensitive to impurities and corrosion.

The liquid feeding them must be carefully filtered.

Maintenance is also critical.

Spinnerets

Spinnerets And Shapes Obtained

> No solvent

recovery.> High Speed

> Simple>

Inexpensive

> Solvent Recovery> Slowest Process

> Additives can be added

> Solvent Recovery> Lower Speeds

> Limited use due to

environmental concerns

Comparison

Melt Wet Dry

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