Method for manufacturing high tenacity fiber and high tenacity fiber manufactured thereby

A high tenacity yarn manufactured by a method, the method comprising:

• firstly coating a yarn made of at least one of nylon and polyester wherein the yarn is fed from a bobbin to a first water bath containing a first coating material, and the yarn is coated with the first coating material while passing over a first roller provided in the first water bath at a speed of about 5 to 30 m per minute, and controlling a thickness of the first coating material coated on the yarn by controlling a degree of contact between a thickness control plate and the yarn by using the thickness control plate provided behind first the roller and being movable relative to the yarn, thus obtaining a firstly coated yarn, wherein the first coating material contains 3 to 35 parts by weight of a reinforcing agent composed of a mineral material per 100 parts by weight of a coating liquid containing polyurethane, and the mineral material is at least one of basalt, glass fiber, and iron in a powder form having a particle size of 30 to 500 μm;
• firstly drying the firstly coated yarn passing through an inside of a first drying furnace, the firstly coated yarn being dried by far-infrared radiation at 100 to 600° C.;
• secondly coating the dried firstly coated yarn with a second coating material which is obtained by diluting the first coating material to have a concentration of 60 to 80%, thus obtaining a secondly coated yarn, wherein the firstly coated yarn is fed from the first drying furnace to a second water bath containing the second coating material, and the firstly coated yarn is coated with the second coating material while passing over a second roller provided in the second water bath;
• and
• secondly drying the secondly coated yarn passing through an inside of a second drying furnace, the secondly coated yarn being dried by far-infrared radiation at 100 to 600° C. and a length of the second drying furnace being shorter than that of the first drying furnace,
• wherein the coating liquid further comprises carbon nanotubes, and, wherein the firstly coated yarn is dried by passing the first coated yarn through the inside of the first drying furnace at a first temperature to activate the carbon nanotubes coated on the yarn, and further wherein the first coated and dried yarn is further dried at a second temperature lower than the first temperature for drying the first coating.