Overview of nylon fabric and its physical and chemical properties

Nylon is the trade name of polyamide fiber produced in my country, and foreign products are called nylon. There are many varieties of polyamide fibers, which can be named according to the number of carbon atoms in the chemical structural unit. Nylon 6 is obtained by polymerization and spinning of caprolactam. Nylon 66 is synthesized from hexamethylenediamine and adipic acid to synthesize polyhexamethylene adipamide through melt spinning. Made of silk and stretching. It has an approximately circular cross-section and has many excellent properties.

There are many varieties of nylon. The main variety used in the textile industry is nylon 6. Nylon 66 nylon can be divided into short fiber, ordinary filament and strong filament in processing. According to gloss, there are three types: light, semi-gloss and special-shaped (flash).

Nylon is a hydrophobic fiber containing alkane bonds, but It also contains hydrophilic groups such as amino (-NH2) and carboxyl (-C00H) terminal groups, so its hygroscopicity is higher than polyester, so although its dyeing performance is not as good as natural fibers, it is easier to dye among synthetic fibers. Dyeing varieties.

Physical properties of nylon

(1) Nylon has good elasticity. This is mainly because its molecular structure contains a large amount of -CH2-, which makes it easy to bend. The molecules in its amorphous region tend to be in an irregular entangled state, so it has excellent tensile and rebound properties, good softness and high elasticity.

(2) Nylon has excellent dry strength and wet strength. higher.

(3) Nylon has a certain degree of hygroscopicity, about the same as polyester 10 times.

(4) Nylon fabric has excellent wear resistance and high About 10 times stronger than cotton fiber.

(5) Nylon fabric has good heat resistance because of its It is a thermoplastic fiber that softens when heated to a certain temperature and melts when the temperature is raised again. Therefore, special attention should be paid when printing and dyeing.

(6) Nylon also has natural moth-proof and mildew-proof properties, making it suitable as a material for decorative fabrics.

Chemical properties of nylon

(1) Nylon has good stability to alkali. When treated with 50% NaOH solution at room temperature, its strength remains almost unchanged. But when the temperature rises above 60°C, the fibers are damaged.

(2) Nylon is sensitive to the action of acids, especially inorganic acids and strong organic acids. Concentrated hydrochloric acid and concentrated sulfuric acid can decompose or completely dissolve nylon.

(3) Strong oxidants also have a damaging effect on nylon. Hydrogen peroxide, potassium permanganate, and sodium hypochlorite can break and degrade its molecular chains. But it has good resistance to sodium chlorite.

(4) It is insoluble in gasoline, benzene, ketone and other solvents, but soluble in phenols .

Due to the physical state of nylon itself such as crystallization, rotation, twist, fiber type, setting condition, the difference in tension before printing, temperature and pH value Changes, etc., often lead to poor leveling of printing and dyeing. On the other hand, its glass transition temperature is lower than that of polyester, and it is also more affected by moisture, so special attention should be paid during printing and dyeing.

When nylon fabric is processed on a rotary screen printing machine, there are limitations in the printing effect, such as thin stems The clarity of the pattern is not ideal, and the leveling properties of large areas are not as good as lithographic screen printing, let alone manual hot plate screen printing. However, rotary screen printing has the characteristic of printing geometric straight patterns. Therefore, nylon umbrella silk is often printed on rotary screen printing machines.