Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/18—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D1/00—Treatment of filament-forming or like material
  • D01D1/02—Preparation of spinning solutions

Definitions

• a large number of processes are known for the production of spinnable solutions from polymerization products, such as, for example, polyacrylonitrile, for the production of synthetic threads and fibers.
• polymerization products such as, for example, polyacrylonitrile
• acrylonitrile polymers can be dissolved in dimethylformamide or another polar organic solvent, such as dimethylacetamide, dimethyl sulfoxide, etc., with stirring at 70-90 ° C., then filtered and spun into threads.
• dimethylformamide or another polar organic solvent such as dimethylacetamide, dimethyl sulfoxide, etc.
• German patent application P 4152 29b, 3/65 should be particularly emphasized, in which a process is proposed in which the comminuted polymer is slurried in solvent and the slurry after being transferred to a heating zone to a temperature (for example 150 ° C.) brings, in which the solvent has a noticeably dissolving effect on the polymer and the resulting clear, colorless solution spins into threads.
• the solution formed in the heating zone is not "kept at an elevated temperature for a substantial time" in order to avoid damage to the color of the solution. According to claim 2 and the examples, this means a duration of approximately 40 seconds.
• sparingly soluble polymers can be processed in a continuous dissolving and spinning process to give threads or fibers which have a good raw tone, the disadvantages described no longer occurring when the sparingly soluble polymers which are used for spinning are combined with the spinning solvent to be used pastes, the suspension is heated for at least 3 minutes, but preferably 5 minutes, to at least 130 ° C., but preferably 150 ° C., and this still inhomogeneous solution is converted into a homogeneous, clear, viscosity-stable spinning solution with a good raw tone, filtered and immediately thereafter feeds the spinneret.
• the invention therefore relates to a process for the continuous production of synthetic non-discolored threads and fibers from thread-forming synthetic polymers which are sparingly soluble in organic polar solvents by producing a suspension of polymer and solvent at room temperature and then heating this suspension, which is characterized in that the suspension is heated to at least 130 ° C for at least 3 minutes, the resulting clear spinning solution is homogenized without intermediate cooling, filtered and immediately spun into threads.
• Suitable solvents are the polar organic solvents customary for this technique, especially dimethylformamide.
• the spinning solutions which are preferably homogenized using static mixers, preferably have a solids content of 24 to 30.5% by weight.
• the spinning solvent for example dimethylformamide
• the polymer solid for example PAN powder
• the resulting clear, yellow solution is discharged into an intermediate vessel, brought to the desired temperature in a secondary solvent and into a venting vessel is pressed.
• a pump then conveys the spinning solution into a spinning kettle, from where it is conveyed through a filter to the spinning machine.
• the residence time of, for example, acrylonitrile homopolymers with a K value of 90 and more at a spinning solution concentration of approximately 25% must be at least 3 minutes, but preferably 5 minutes, in order to obtain viscosity-stable solutions.
• the dwell time of the spinning solution at high temperatures of 130 ° C. and more must be extended accordingly.
• titer fluctuations usually still occur, which occur in the end product in the form of bristles.
• intensive mixing of the spinning solution before or after the filtration has proven to be particularly suitable.
• Usable aggregates are, for example Static mixing elements in the form of combs, honeycomb grids, lamellas or spirals, whereby usually several elements are rotated 90 ° against each other, arranged one behind the other.
• An embodiment in which the mixing element is arranged directly in front of the spinneret has proven to be particularly favorable. In this way, intensive homogenization and good heat exchange as well as optimal concentration, viscosity and temperature compensation are achieved.
• Suitable units for rapid solution preparation are, for example, double-walled tubes which are heated with steam at a pressure of about 3-5 bar, so that the temperature of the solution at the tube outlet is 130-150 ° C.
• this embodiment of a heating device can be structurally dimensioned such that corresponding dwell times of at least 3 minutes can be set.
• the viscosity of the spinning solutions is expressed in falling ball seconds (measured according to K. Jost, Rheologica Acta, Volume 1, No. 2 to 3, (1958), page 303). Unless otherwise noted, parts and percentages relate to weight.
• a 5% solution of the corresponding fiber sample in dimethylformamide is prepared by treatment at 100 ° C. for 30 minutes. The mixture is then cooled to room temperature and, if it is still slightly cloudy, the solution is centrifuged off and measured in a 1 cm cuvette at 420 nm in comparison with pure DMF using the Elko II device from Zeiss.
• a color number up to approx. 0.25 visually represents bright white fibers. Color numbers from about 0.25 to about 0.35 represent a yellowish cream to cream-colored raw tone and color numbers above 0.35 stand for a light yellow to lemon-colored appearance of the fibers.
• the spinning solution is filtered, passed through a tube which is equipped with a plurality of mixing combs, and then dry-spun from a 96-hole nozzle according to procedures which are known in the art.
• the spun material with a titre of 1670 dtex is then drawn on a draw twister 1: 9.6 times over hot godets at 150 ° C. Perfect running behavior, without capillary cracks. Fiber strength 4.2 centinewton / dtex, elongation at break 11%. Cross-sectional microscopic images show no fluctuations in titre and sticking.
• Table 1 below shows further experiments with acrylonitrile homopolymer of different solids concentration. All polymers were as described in Example 1, spun into fibers with a final titer of 2.8 dtex and textured. The texturing was smooth in all cases. As can be seen from Table 1, good processing properties are achieved even with highly concentrated spinning solutions made of acrylonitrile homopolymer, while changing the cross-sectional structure. The raw tone is optically bright white in all cases.
• Analogous amounts of dimethylformamide and acrylonitrile homopolymer, as described in Example 1, are pasted in a screw and the slurry of solution is fed into a kettle. There, the slurry is heated to 90 ° C. with stirring for 3 hours, a solution which is not yet completely homogeneous being formed. This can be seen from the undissolved particles and jellyfish still present in the solution, so that the solution appears optically cloudy when viewed through. This unfinished solution is then heated to 120 ° C until the solution is no longer visually cloudy. After 30 minutes the solution is then filtered and spun directly as described in Example 1 / into threads with a total titer of 1670 dtex.
• Table 2 lists further tests varying the residence time and the temperature of the spinning solution in the heating device described in Example 1.
• the dwell time of the spinning solution was also changed via the number of heating devices used.
• the raw tone of the fibers is good in all cases and improves with decreasing temperature load.
• the spinning solution should be brought to 130 ° C for at least 3 minutes in order to achieve viscosity-stable solutions. This is the only way to ensure trouble-free running on the streching machine.
• Table 3 shows further tests with different solids concentrations. All of the polymers were spun into fibers with a total titer of 1670 dtex, as mentioned in Example 15, and then drawn on a stretching machine 1: 9.6 times on a trial basis. As can be seen from Table 3, the spinning pattern (increase in titre fluctuations, bonds and bristles) deteriorates with increasing polymer solids concentration. With the omission of the static mixing combs, virtually no processing on the draw twisting machine can be achieved. (Strong tendency to wrap, capillary breaks, fluffy material).

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Artificial Filaments (AREA)
• Multicomponent Fibers (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

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• 1979
  • 1979-01-18 DE DE19792901860 patent/DE2901860A1/de not_active Withdrawn
• 1980
  • 1980-01-07 DE DE8080100055T patent/DE3063554D1/de not_active Expired
  • 1980-01-07 AT AT80100055T patent/ATE3654T1/de not_active IP Right Cessation
  • 1980-01-07 EP EP80100055A patent/EP0013889B1/fr not_active Expired
  • 1980-01-17 JP JP315380A patent/JPS5598910A/ja active Granted
  • 1980-01-17 IE IE92/80A patent/IE49247B1/en unknown
• 1981
  • 1981-07-02 US US06/279,898 patent/US4427613A/en not_active Expired - Lifetime

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