Polyamide yarns are mainly produced in a continuous / filament version and in two basic types - PA6 and PA66.
Polyamide spun yarns are rarely produced. These are the possible blends:
Currently, about 5 million tons of all polyamide yarns and fibers are produced annually in the world. This accounts for around 6% of the world production of all yarns.
Main properties of polyamide yarns:
- high breaking strength
- abrasion and friction resistant (flat version)
- good moisture absorption
- friendly to human skin / does not cause allergies
- very soft and silky touch
- stains are easily removable
Due to the above properties polyamide yarns are used in the production of underwear such as pantyhose, socks, body seamless, bras, sportswear, swimwear and in medical textiles.
High breaking strength and resistance to high temperatures make polyamide yarns widely used in tire cords, industrial hoses, conveyor belts, technical belts, parachutes, ropes, technical nets, fishing nets, industrial threads.
PA6 was invented and put into mass production in Germany in 1939. PA66, on the other hand, was invented and introduced into mass production by DuPont in the 1940s in the USA.
Both types of polyamide are formed as a result of a polymerization reaction, where the basic raw materials are petroleum derivatives - CPL (caprolactam) and adipic acid.
Polyamide is a fiber spun from melted granulate (polymer). The result of spinning process is POY - raw material for further processing or a ready-to-use flat FDY / HT yarn.
Flat FDY / HT yarns after spinning and cooling are drawn to achieve the target physico-mechanical properties, such as strength and elongation,which ensure good processing on the machines.
By modifying the batch polymer and the spinning and drawing process, we obtain flat high tenacity yarns (HT).
If we add to the polyamide polymer more titanium dioxide (TiO2) than standard we will obtain full dull yarns as opposed to the standard semi-dull shade.
By modifying the spinnerets, we can obtain trilobal bright polyamide yarns.
If the masterbatch is added to the polymer before spinning, the result is POY / FDY / HT dope dyed.
POY, i.e. the raw material for further processing, is spun and cooled, however, it is not drawn which results in its high elongation and low tensile strength. This type of production is not suitable for processing on weaving or knitting machines.
To obtain a crimpy and elastic polyamide yarn, POY has to be textured on ceramic or polyurethane discs .
The density of polyamide (both PA6 and PA66) is around 1.14 g / cm3. This is therefore a value higher than of polypropylene, but lower than of polyester.
PA6 has a melting point of 210 degrees Celsius and PA66 of 260 degrees Celsius. The high melting point, especially for PA66 yarns, makes these yarns applicable wherever resistance to high temperatures is needed.