METHOD FOR HYDROCELLULOSE BUNDLE PRODUCTION Russian patent published in 2017 - IPC D01F2/08 D01D10/00 

FIELD: chemistry.

SUBSTANCE: method for hydratocellulose bundle production, characterized by dilution of sulfite or sulfate cellulose with cellulose mass fraction αof at least 94% and polymerization degree of 800-900 in a previously prepared concentrated phosphoric acid, represented by an orthophosphoric acid mixture containing 14-15 wt % of pyrophosphoric acid. The prepared concentrated phosphoric acid is fed into the sealed reactor capacity, heated to a temperature of 40-45°C at stirring with the activator speed rotation of the 1-5 rpm for 30-40 min and without changing the rotator speed, the cellulose crushed to fluff is loaded for 15 minutes, then stirring is continued at a speed of 40-50 rpm during 20-25 minutes at a temperature of 40°C till the stage of loose cellulose suspension formation at simultaneous evacuation of the sealed reactor capacity at a residual pressure of 0.01 MPa, the resulting cellulose suspension is cooled for 60-70 minutes to a temperature of minus 10 to minus 12°C with liquid nitrogen feeding into the reactor jacket, as a cooling agent, with cellulose suspension transfer to the gel-like state of spinning solution with a viscosity of 10.000-15.000 Pa⋅s, then the resulting highly viscous gel-like spinning solution is fed to the extrusion unit, heated to a temperature of 25-35°C and supplied with a gear pump in a volume of 10 cm of high-viscosity gel-like spinning solution of cellulose for 1 pump revolution, and fed for filtration into a flat filter in the form of a three-layer stainless steel grid of, then a high-viscosity gel-like spinning solution of cellulose with phosphoric acid mass fraction (H₃PO₄+H₄P₂O₇) of 73-74% in terms of P2O5, cellulose mass fraction of 17.0-17.2%, with spinning solution viscosity of 1000-1500 Pa⋅S at a temperature of 25-35°C is extruded through a spinneret with 1180 holes with a diameter of 60 mcm through an air gap of 1 to 20 mm into the coagulation zone of the precipitation bath for hydrocellulose bundle formation, filled with acetone as a coagulant, containing 10-12 wt % of phosphoric acid, at the precipitation bath coagulant temperature of 15-25°C, and a hydrocellulose bundle is formed at a forming speed of 75-80 m/min and extractive coefficient of 2-10 with freshly formed fiber transfer to the conveying rollers. Diameter of a filament of the initial hydrocellulose fiber is 8.5 to 15 mcm at a linear density of 0.13-0.17 tex, then a unidirectional bundle of the obtained hydrated cellulose fiber is impregnated with an aqueous solution of ammonium chloride with NP4Cl concentration in an amount of 150-200 g/l, containing urea with concentration (NH₂)₂CO in an amount of 10-30 g/l, or an aqueous solution of ammonium sulfate with (NH₄)₂SO₄ concentration in an amount of 250-300 g/l, containing urea with (NH₂)₂CO concentration in an amount of 20-40 g/l, as a flame retardant, drying of the impregnated bundle of initial hydrocellulose fiber is carried out at a temperature of 120-140°C for 30-60 minutes.

EFFECT: as a result, carbon fiber at the maximum carbon content with a given specific electrical resistance can be obtained from a hydrocellulose bundle with the specified properties, with high strength tensile properties of both the elementary carbon fiber and its bundle as a whole.

2 cl, 6 ex