High-speed process for producing acrylic fibers and relative apparatus
AssigneeMontefibre Mae Technologies S.r.l.
InventorsFranco Francalanci, Pierluigi Gozzo, Ana Paula Vidigal, Marco Rovellini, Valter Guardiani
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Abstract
A process for the production of acrylic fibers, in particular a spinning process for obtaining precursor fibers of carbon fiber by the wet spinning of a polymer solution in an organic solvent and the relative apparatus.
Claims17
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.
A wet-spinning apparatus, comprising at least one washing or washing and stretching unit U, said unit U comprising:
- a washing tank configured for containing a washing solution;
- wherein said solution is fed to a first end of said tank at a first temperature T1 and wherein said solution is discharged at a second end of said tank at a second temperature T2, said temperature T1 being higher than said temperature T2;
- mechanical means configured for moving a tow or bundle of filaments from said first end to said second end of the tank;
- wherein in the washing tank, the movement direction of the washing solution is in co-current with respect to the movement direction of the tow or bundle of filaments;
- and
- further wherein the solution being discharged at the second end of said washing tank at the second temperature T2, is fed through an overflow and a filter to an auxiliary recycling tank where a first portion of said solution is fed by means of a pump to an auxiliary heating tank, equipped with a heat exchanger, said auxiliary heating tank being configured for feeding said washing solution to the first end of said washing tank at the first temperature T1.
A wet-spinning apparatus, comprising two or more washing or washing and stretching units U, arranged in sequence and fluidly connected to each other, said apparatus comprising:
- a washing tank configured for containing a washing solution;
- wherein said solution is fed to a first end of said tank at a first temperature T1 and wherein said solution is discharged at a second end of said tank at a second temperature T2, said temperature T1 being higher than said temperature T2;
- mechanical means configured for moving a tow or bundle of filaments from said first end to said second end of the tank;
- wherein in the washing tank, the movement direction of the washing solution is in co-current with respect to the movement direction of the tow or bundle of filaments;
- and
- further wherein the feeding of the washing solution is in countercurrent with respect to the movement direction of the tow or bundle of filaments with respect to the sequential arrangement of the washing or washing and stretching units U.
Dependencies are inferred from the claim text.