CPC D01F 6/38 (2013.01) [B08B 3/041 (2013.01); B08B 3/048 (2013.01); D01D 5/06 (2013.01); D01D 10/00 (2013.01); D01D 10/06 (2013.01); D01D 11/00 (2013.01); D01F 9/22 (2013.01); D01H 13/02 (2013.01); D10B 2321/10 (2013.01); D10B 2401/063 (2013.01)] | 17 Claims |
1. A method of spinning a homogeneous solution of acrylic copolymer in organic solvent for the production of precursor fibers including a wet-spinning step comprising spinning homogeneous solution at a speed ranging from 150 to 400 m/min, wherein
the homogeneous solution of acrylic copolymer in organic solvent or dope is fed to one or more spinnerets with a hole diameter ranging from 150 to 300 microns, said spinnerets being immersed in a coagulation bath consisting of a mixture of organic solvent and non-solvent solvent with a concentration of organic solvent ranging from 78 to 85% by weight, with respect to the total weight of the mixture, at a temperature ranging from 5 to 40° C.;
the dope at the outlet of said one or more spinnerets comes into contact with the coagulation bath where it coagulates forming a tow or bundle of filaments, with a jet stretch ranging from 5 to 15, said jet stretch being the ratio between the outlet speed of the dope from the spinneret into the coagulation bath and the collection speed after coagulation;
said tow or bundle of filaments then being fed to a series of washing or washing and stretching steps, wherein each washing or washing and stretching step is carried out in co-current, a movement direction of a washing solution coinciding with a movement direction of the tow or bundle of filaments, a feeding and discharging of the washing solution in each washing or washing and stretching step being carried out in countercurrent with respect to the movement direction of the tow or bundle of filaments.
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