Flow Chart of Nylon 6 Manufacturing Process

Nylon 6 is made from one component namely Caprolactum, which has six carbon atom. Nylon 6 fibers are tough, possessing high tensile strength, as well as elasticity and luster. They are wrinkle-proof and highly resistant to abrasion and chemicals such as acids and alkalis. The fibers can absorb up to 2.4% of water, although this lowers tensile strength. The glass transition temperature of Nylon 6 is 47 °C. Nylon 6 Manufacturing Process is as follows:

Meltzer
↓
Mixing tank
↓
Filter
↓
Autoclave
↓
Condensation polymerization
↓
Melt spinning
↓
Drawing
↓
Texturization

Nylon 6 is produced by ring-opening chain-growth polymerization. In presence of water vapor and an acid catalyst at the melt. After removal of water and acid, the nylon 6 is melt-spun at 250°–260°C into fibers. Nylon 6,6 is prepared by step-growth polymerization of hexamethylene diamine and adipic acid. After drying, the nylon 6,6 is melt-spun at 280°–290°C into fibers.

Mechanical Properties

1. Density: 1.14 g/cc
2. Tenacity: Dry= 4.2-5.8 gpd, Wet=4.0-5.3 gpd
3. Elongation at Break: Dry = 24-40, Wet= 28-43
4. Elastic Recovery at 4% extension= 100%
5. Moisture Regain= 4%
6. Because of low MR, wet nylon dries quickly.
7. Melting Point= 215 deg ºC ( Nylon 66-250 deg º C)
8. It is weakened by prolonged exposure to sunlight.

Chemical Properties

1. It is resistant to most organic acids such as benzene, chloroform, acetone, esters ethers, etc.
2.  It dissolves in phenol, cresol, and strong mineral acids.
3. good resistance towards alkalies.
4. Resistant to inorganic acids

These fibers are cylindrical in shape, with smooth surfaces, and without having any markings. The fibers are uniform in diameter and appear round in cross-section.

Application of Nylon 6:

a. Tyre Cord Manufacturing
b. Fishing Lines
c. Luxury Yachts
d. Stockings with good fit, sheerness, quick washing, and drying properties.

Nylon 6 has certain advantages over Nylon 6,6. The synthesis of caprolactam is easier than that of Hexamethylene Diamine and Adipic Acid. Therefore it is cheaper to make Nylon 6 than Nylon6,6. Furthermore, nylon 6 has a greater affinity for acid dyes than Nylon6,6.

Author of this Article:
Muhammad Ibrahim Khalilullah 
Department of Textile Engineering 
Daffodil International University 
Email: ibrahim23-3123@diu.edu.bd