Lyocell multi-filament for tire cord and method of producing the same
Disclosed is a lyocell multi-filament for a tire cord and a method of producing the same. The method includes i) dissolving mixed powder of cellulose and polyvinyl alcohol in a mixed solvent of N-methyl morpholine N-oxide and water to prepare a dope, ii) extruding the dope using a spinning nozzle including orifices through air gaps into a conical upper coagulation bath to solidify the dope to produce a multi-filament, iii) feeding the multi-filament through a lower coagulation bath to a washing bath, and washing the multi-filament, and iv) drying and oiling the washed multi-filament and winding the resulting multi-filament. At this time, the orifices each have a diameter (D) of 100 to 300 μm, a length (L) of 200 to 2400 μm, and a ratio of the length to the diameter (L/D) of 2 to 8, and are spaced apart from each other at intervals of 2.0 to 5.0 mm. The method provides a lyocell multi-filament having excellent physical properties useful as a tire cord, thereby producing a tire for an automobile having improved driving stability, dimensional stability, and uniformity using the tire cord.
1. A lyocell multi-filament having tenacity of 5 to 10 g/d, elongation of 3 to 13%, modulus of 200 to 400 g/d, birefringence of 0.038 to 0.050, crystallinity of 40 to 52%, shrinkage of −0.5 to 3%, strength maintenance after a high 15 temperature and saturated vapor treatment of 90% or higher, and fineness of 1000 to 2500 deniers.
2. The lyocell multi-filament as set forth in claim 1 , wherein elongation is 0.5 to 4.0% at a load of 4.5 kg.
3. The lyocell multi-filament as set forth in claim 1 , wherein a load at break is 5.0 to 25.0 kg.
4. A tire cord comprising the lyocell multi-filament according to claim 1 .
5. A dip cord for tire cords produced using the tire cord according to claim 4 .
6. The dip cord as set forth in claim 5 , having fineness of 3000 to 6000 deniers, twist constant of 0.67 to 0.85, and a load at break of 14.0 to 28.0 kg.
7. A tire for automobiles comprising the lyocell multi-filament according to claim 1 .
8. A tire comprising the dip cord according to claim 5 .
9. A tire cord comprising the lyocell multi-filament according to claim 2 .
10. A tire cord comprising the lyocell multi-filament according claim 3 .
11. A tire for automobiles comprising the lyocell multi-filament according to claim 2 .
12. A tire for automobiles comprising the lyocell multi-filament according to claim 3 .