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

Definitions

• This invention relates to, an improvedv process for the formation of shaped. polymeric materials.
• this invention is concerned with an improved method for wet-spinning acrylonitrile; polymer and copolymers, thereof contain,- ing at least; 85% acrylonitrile.
• the processof this invention is generally applicable to the production of any shaped article, as, for example, yarns, films,.b.r.istles. tubing and the. like.
• the discussion herein is directed chiefly to. the production of yarns of polymers of acrylonitrile by the wet. spinning method.
• 120 15.0150. may be employed as, a coagulating bathto produce yarn having a dry tenacity of 2 to 4 grams per denier.
• polymer solvents. having high boiling points In this casev the. use of hot ycerol as a spinning. bathdoes not lead. to maximum yarn ten'acities because the yarn sets up very slowly. Under these conditions extreme care and a long. bath, travel are required to complete coagulation.
• special spinning rollers must. be used in the bath to prevent. the development of high tensions prior ta the wind-up because the yarn sets up so slowly. These disadvantages slow the rate of production materially and the process is not of commercial value.
• a spinning procedure which would permit the use of friction snubbing devices normally used in wet-spinning would considerably simplify the process and. allow the production of. higher tenacity yarns. under optimum conditions.
• This invention has as. an object. the improvement of yarn properties of polyacrylonitrile and.
• a further object is the provision of coagulating baths which permit faster coagulation of wet-spun. yarn.
• a still further object. is the provision of spinninsmetm;
• v Etcamples Eleven parts of acrylonitrile. polymer, prepared by the polymerization of monomeric. acrylonitrile in accordance with the teachingsof U. S. Patent. No. 1160;0541 to Bauer et al'.,.and possessing an average molecular weight of 89,000: as determined by the Staudinger equation from viscosity data, are ground to an average particle size. of v mesh and mixed with 89.. parts of tetramethylene sulfone to form a thin slurry. Air entrapped in the polymer slurry is removed using vacuum techniques: The'slurryis then heated to C.
• a suitable solvent within the scope of this invention is one with a rather high boiling point i. e., above 200 C.
• a solvent of fairly low boiling point e. g., dimethylformamide
• the glycerol bath at the temperatures employed acts to set up the yarn at a conveniently fast rate and no water dip is required for attainment of high yarn porperties.
• solvents having a high boilin point say above 200 C.
• the glycerol temperatures used do not remove solvents from the coagulating filament at a desirable rate. This occurs probably, because the low vapor pressure of the solvent at the spinning temperatures causes relatively little solvent to be removed by evaporative processes and only solution processes arising from the solubility of the solvent in the bath are operative.
• the use of a water dip results in a considerable increase in rate of coagulation with consequent improvement in the physical properties of the yarn.
• tetramethylene sulfone is described herein as a suitable solvent for the wet spinning of polyacrylonitrile by this invention, it is to be understood that the method may be applied to spinnin from other solvents as well.
• suitable polyacrylonitrile solvents which are useful in the process of this invention are the water-soluble solvents disclosed in U. S. Patents Nos. 2,404,714-2,404,727, inclusive, which possess high boiling points, for example, in excess of 200 C.
• this invention is applicable broadly to the use of any high boiling water-soluble organic solvents for the acrylonitrile polymers.
• Specific solvents which may be mentioned here for; illustrative purposes include malononitrile, methyl ethyl sulfoxide and methyl ethyl sulfone.
• the temperature of the water dip may be varied from 0 to 100 C. Room temperature, however, is most convenient and. gives excellent results.
• the glycerine bath temperatures may be from 100 C. to 160 C., but a temperature of about 140 C. gives optimum yarn properties.
• the length of travel of the yarn through the glycerine and water baths depends upon the rate of coagulation of the yarn. The bath length will also vary directly with the spinning speed. Since the water dip accelerates the rate of yarn coagulation, the length of travel through the glycerine bath can be much less than when used without a water dip. The use of the water dip as described herein accelerates the rate of coagulation of a spinning solution from 10 to 75% or more.
• the spinning tensions are applied by means of the usual friction snubbing devices described elsewhere in the wet-spinning art. Yarns spun from high boiling solvents without an intermediate water dip cannot be subjected to the desired spinning tension, because of the slow rate of coagulation. Since yarns spun under low tension do not develop optimum properties, it is especially advantageous to be able to subject the yarn to tension as it coagulates.
• the after-stretch ratio for wet-spun acrylonitrile polymer usually is somewhat lower than that experienced with dry spun yarn. Generally, this ratio may be from 1.5X to 9X with the range of 1.'75X to 5X preferred.
• the temperature of the after-stretching largely depends on the physical and chemical properties of the polymer.
• after-stretch ing temperatures of C. to 210 C. are possible with the range C. to 0. preferred.
• the yarn after-stretching may be carried out on any suitable apparatus which allows the yarn to be heated prior to drawing.
• a preferred process and apparatus is described in the copending application of Daniel T. 'Meloon, Serial Number guesses 496,397, filed July 28; 1943, nowabandonded. Another process might bethe drawing ofthe yarn as it passes through a heated medium, such;
• the preferred temperature range is considerably lower, 1. e., 110 C. to 140 C.
• a greater degree of elongation in. the finished yarn may be obtained by allowing the yarn to relax (5-15%) immediately after drawingmay be accomplished by passing the yarn over a hot plate or through a heated atmosphere at a temperature slightly above the draw temperature and allowing the yarn to relax (contract) the desired amount by running the take-up roll the desired relaxed ratio percentage slower than the feed roll.
• the heat-treating of polyacrylonitrile yarn to improve elongation without loss in tenacity may be carried out by heating the yarn cones in a thermostatically controlled oven or other suitable means.
• the time of heat treatment will normally vary inversely with the temperature. Depending upon the heat-treating temperature, the time may be varied from 1 to 10 hours at temperatures of 100 C. to 200 C.
• the preferred range of temperature is 100 C. to 150 C, for a treatment time of /2 to 2 hours.
• the polymers for use in this invention preferably have molecular weights within the range of 15,000 to 250,000 or even higher as calculated from viscosity measurements by the Staudinger equation:
• C concentration of the solution expressed as the number of moles of the monomer (calculated) per liter of solution.
• Polyacrylonitrile itself may be used and copolymers of acrylonitrile with such monomers as vinyl esters, vinyl halides, vinylidene halides or other ethylenic compounds such as ethylene or butadienes may be employed in the process of this invention.
• the vrocess of this invention allows the use of high boiling solvents that would otherwise have little commercial value due to the excessive length of time necessary to set up the yarn as it is spun.
• high boiling solvents can be used at temperatures considerably below their boiling point, thus making commercially available a large num- 6. her of suitable solvents for the spinning of polyacrylonitrile yarns.
• a process for wet spinning'of yarn of an acrylonitrile polymer containing at least of acrylonitrile which comprises extruding a solution of said polymer in a high-boiling, watersoluble organic solvent through a shaped orifice into a first coagulant spinning bath selected from the group consisting of glycerol, triethanolamine and hexaethylene glycol, thereby precipitating said polymer from its said solution in the form of yarn; passing said yarn into a second coagulant bath consisting of water; and subsequently into a third coagulant bath selected from the group consisting of glycerol, triethanolamine and hexaethylene glycol, and stretching said yarn during the spinning.
• a first coagulant spinning bath selected from the group consisting of glycerol, triethanolamine and hexaethylene glycol
• a process for wet spinning of yarn of an acrylonitrile polymer containing at least 85% of acrylonitrile which comprises extruding a solution of said polymer, in a high-boiling, watersoluble organic solvent, through a shaped orifice into a spinning, coagulant bath consisting of glycerol heated to a temperature of at least 100 C.; passing the yarn formed thereby into a second coagulant bath consisting of water heated to a temperature from about 20 C. to about 100 0.; and passing said yarn into a third coagulant bath consisting of glycerol heated to a temperature of at least 100 C.; and stretching said yarns during the spinning.
• a process for Wet spinning of yarn of an acrylonitrile polymer containing at least 85% of acrylonitrile which comprises extruding a solution of said polymer in tetramethylene cyclic sulfone through a shaped orifice into a first coagulant spinning bath selected from the group consisting of glycerol, triethanolamine and hexaethylene glycol, thereby precipitating said polymer in the form of yarn from a solution comprising about 89% tetramethylene cyclic sulfone and about 11% said polymer; passing the yarn formed thereby into a second coagulant bath consisting of water; passing said yarn from said second bath into a third coagulant bath consisting of glycerol; and stretching said yarn during the spinning.
• a first coagulant spinning bath selected from the group consisting of glycerol, triethanolamine and hexaethylene glycol
• a process for wet spinning of yarn of an acrylonitrile polymer containing at least 85% of acrylonitrile which comprises extruding a solution of said polymer in a high boiling water soluble organic solvent through a shaped orifice into a glycerol coagulant spinnin bath heated to a temperature of about 100 (3., thereby precipitating said polymer from its said solution in the form of yarn; passing the said yarn through the said glycerol coagulant spinning bath for a distance'of about 2'7 inches; passing 'said-- yarn through a second coagulating bath'consisting of 7 REFERENCES CITED
• the following references are of record in the file of this patent:

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• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)

Priority Applications (4)

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Publications (1)

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Cited By (4)

Citations (5)

• 0
  • NL NL138683D patent/NL138683B/xx unknown
  • NL NL72124D patent/NL72124C/xx active
  • FR FR961050D patent/FR961050A/fr not_active Expired
• 1947
  • 1947-02-13 US US728372A patent/US2555300A/en not_active Expired - Lifetime

Patent Citations (5)

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