Introduction of Nylon 6 Fiber | Spinning Process of Nylon 6 Fiber |Manufacturing Process of Nylon 6 Fiber

Nylon 6 Fiber

The synthetic fibres also called as chemical fibres are the synthesised polymers, which are not found in nature. There are different types of synthetic fibres of which the manufacturing process of nylon is discussed in this unit. Nylon is the first man made synthetic fibre (pure chemical fibre).

Nylon 6 Fiber

As defined by the Federal Trade Commission (FTC), nylon “is a long – chain synthetic polyamide in which less than 85 per cent of the amide linkages are attached to two aromatic rings”.

Manufacturing of Nylon 6
The raw material for manufacturing Nylon 6 is coal.Cyclohexane oxime is produced by a series of chemical reactions on coal. Cyclo heaxaneoxime is then treated with sulphuric acid to form caprolactum. The caprolactum is a monomer with 6 carbon atoms that are polymerized to from chains of caprolactum. Polymerization is done by gently heating it in a steam – jacked stainless steel vessel. The solution is stabilised as a super polymer under constant steam and pressure.

Nylon may be delustered by adding the delustering agents like titanium di oxide, barium sulphate, zinc oxide, and zinc sulphate. The molten nylon 6 polymer is allowed to flow onto a slowly revolving casting wheel. These are sprayed with cold water, which hardens it into milky white ribbons. The ribbons are transformed into flakes that are sent for spinning and are then drawn into the fibre form.

Spinning of nylon 6:

Spinning of Nylon 6
The spinning of the nylon fibres is carried out with melt spinning. There are two methods of melt spinning:

1. grid spinning
2. extruder spinning.

Grid spinning is employed for the production of finer filaments.The nylon flakes are made to fall on a hot grid that melts the nylon flakes. The molten nylon is pumped through a sand filter to the spinneret. The type of filament produced depends upon the number of holes on the spinneret, the size and the shape of the holes. The molten nylon as extruded from the spinneret solidifies and forms filaments as exposed to the air. Extruder spinning is generally used for heavier yarns.

The nylon chips flow by gravity into a device that forces them by screw action through the heated zones. The combined action of the heat and screw pressure melts the chips. The molten polymer is then extruded through the spinneret, which solidifies when the polymer comes in contact with the air.

Drawing:
The filaments obtained from spinning are stretched by drawing process. The drawing process is accomplished in two stages: unwinding the yarn from one godet, or wheel, winding it onto another godet that is rotating much faster. The speed of the second wheel determines the amount of cold-drawing or stretching. The yarn from the second godet is wrapped on a cylindrical tube called a pirn.

The filaments can be stretched from 2 to 7 times their original length. The molecules in the filament structure straighten out, become parallelized, and are brought very close together.