Patent ID: 7732048

Claim:
Cellulose multi-filament yarn produced by a method comprising the steps of: (a) preparing a cellulose solution by swelling and homogenizing a cellulose powder into an aqueous concentrated N-methyl morpholine N-oxide (NMMO) solution; (b) obtaining a multi-filaments by spinning said cellulose solution with a spinning nozzle having 500 to 2000 orifices and a distributing plate having 50 to 300 holes and subsequently precipitating the cellulose solution into a coagulating bath at a temperature of 0 to 35° C. through an air gap wherein the air is 5 to 30° C. in temperature and 10 to 60% in humidity is blown into the air gap at 0.5 to 10 mm/sec air speed; and (c) water-washing, drying with a drying roller maintained at a temperature of 80 to 170° C., treating the multi-filaments with a finishing oil and winding said multi-filaments, wherein the multi-filament yarn is characterized by the following physical properties: 700 to 3000 in denier of original strands; 4 to 9 g/d and 4 to 15% in strength and breaking elongation of the multi-filaments, respectively; a specific breaking time of 3 to 33 sec/denier; and when said multi-filaments are divided into three parts and 100 mono-filaments selected from each part of said three parts have following physical properties: 3 to 9 g/d in strength, 7 to 15% in breaking elongation and 0.035 and 0.055 birefringence, respectively; the differences of average strength, average breaking elongation and average denier are less than 1.0 g/d, 1.5% and 0.7 denier, respectively; CV (coefficient of variation) of average strength, average breaking elongation and denier of said three parts less an 10%; and the differences of average birefringence of said three parts are less than 0.004.