Patent ID: 7713459

Claim:
A method of producing a cellulose fiber comprising the steps of: (A) preparing a cellulose solution by swelling and homogenizing a cellulose powder having a diameter no more than 300 μm into an aqueous concentrated N-methyl morpholine N-oxide (NMMO) solution with 10 to 15 wt % of moisture; (B) passing the cellulose solution through a distributing plate having 50 to 300 holes having a diameter of 50 to 200 mm; (C) obtaining multi-filaments by spinning the cellulose solution with a spinning nozzle having 500 to 2000 orifices and subsequently precipitating the cellulose solution into a coagulating bath through an air gap; and (D) water-washing, drying, treating with a finishing oil and winding the multi-filaments, which filaments so produced which have the following physical properties: (1) 700 to 3000 in denier of the multi-filaments; (2) 4 to 9 g/d and 4 to 15% in strength and breaking elongation of the multi-filaments, respectively; (3) when the multi-filaments are divided into three parts and 100 mono-filaments selected from each part of the three parts have the following physical properties; a) 3 to 9 g/d in strength, 7 to 15% in breaking elongation and 0.035 and 0.055 birefringence, respectively; b) 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; c) CV (coefficient of variation) of average strength, average breaking elongation and denier of the three parts less than 10%; and d) the differences of average birefringence of the three parts are less than 0.004.