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 a process for producing shaped articles such as fibers, ribbons, films, etc., by wet-spinning ethylene carbonate spinning solutions of acrylonitrile polymers and copolymers. More particularly, this invention is concerned with a spinning method which is capable of being conducted continuously for prolonged periods of time with improved efiiciency and yet without sacrificing uniformity, color or other desirable physical properties of the spun articles, hereinafter referred to as fibers. Further, it is concerned with a wet-spinning method in which the loss by decomposition, resinfication, etc. of the ethylene carbonate solvent and the coagulant employed is substantially minimized.
• spin bath compounds which are capable of coagulating such polymeric solutions usually present one or more of the following difliculties: ((1) the coagulant is poor in that weak fibers are produced or in that it can be used only at slow spinning speeds; (b) the coagulant causes excessive decomposition of the ethylene carbonate solvent, particularly when operating at elevated bath temperatures; (0) the coagulant, during spinning and bath recovery operations, decomposes and may form corrosive acidic materials or toxic decomposition products; such decomposition products may discolor the fibers.
• the unstable nature of the ethylene carbonate solvent presents one of the difficulties which must be overcome to achieve successful wet-spinning of polymeric acrylonitrile solutions thereof. Since it is an ester, it undergoes hydrolysis in aqueous solutions, and particularly, under aqueous alkaline or acidic conditions. Moreover, this ester undergoes considerable transesterification in the presence of most alcohols, e. g. monohydric or polyhydric alcohols. The extent of such decomposition by hydrolysis or alcoholysis, is materially increased at the elevated temperatures which are employed during a spinning cycle such as, for example, elevated bath temperatures, e. g., 80 to 150 C., or elevated vacuum distillation temperatures for separating or purifying the bath components, or under both conditions.
• the lower glycols notably ethylene glycol and its higher homologues such as propylene glycol, trimethylene glycol and 2,3,- or 1,3-butylene glycol, although showing a lesser tendency to undergo transesterification than glycerol, are nevertheless poor coagulants. With such coagulants, it is not only necessary to employ very low spinning speeds, but in addition, the yarns produced have excessive voids and low tenacit1es.
• the higher glycols some of which are capable of yielding good fibers at satisfactory speeds, undergo similar transesterification with ethylene carbonate when brought together as a heated coagulating bath liquid.
• these higher glycol coagulants may be mentioned the glycol ethers such as diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and other higher polyalkylene ether glycols.
• 1,4-butanediol 1,5-pentanediol, 2-methylpentanediol-2,4,thiodiglycol and other similar glycols.
• the above difllculties encountered in the wet-spinning of ethylene carbonate solutions of acrylonitrile polymers are substantially eliminated, and fibers having desirable properties and appearance are produced with facility and efficiency.
• a new coagulant is employed which is relatively non-reactive with ethylene carbonate, thus, substantially minimizing solvent and coagulant losses due to decomposition, resinification, etc.
• the new coagulant can be easily washed from a freshly coagulated fiber by means of water, is non-corrosive, and further, is not only relatively free from toxicity but also possesses a low volatility which minimizes mechanical losses by evaporation, etc.
• dipropylene glycol should be different from all of the above-mentioned glycols in that when used as a coagulating bath for the wet-spinning of acrylonitrile polymer solutions in ethylene carbonate, it showed practically no transesterification with the ethylene carbonate and yet yielded high tenacity fibers at high spinning speeds.
• This behavior diflerence may be due, for example, to the differences in each compound in the relative positions of the two hydroxyl groups to each other, their secondary nature, other steric factors, or a combination of such factors.
• the dipropylene glycol coagulant may, however, contain minor quantities of other materials or impurities such as,'for example, other polyhydric alcohol compounds.
• other materials or impurities such as,'for example, other polyhydric alcohol compounds.
• the spin bath exclusive of ethylene carbonate, consists essentially of dipropylene glycol.
• technical and commercial grades of dipropylene glycol usually containing varying minor quantities of other polyhydric alcohol compounds may be conveniently employed. The presence of such extraneous polyhydric alcohol compounds in technical grade dipropylene glycol is usually due to the particular method of manufacture and refinement, if any.
• extraneous materials may be mentioned ethylene glycol, diethylene glycol, propylene glycol, and tripropylene glycol. These may be found in the commercial products in quantities varying up to 5 or 10%, depending upon the source of the dipropylene glycol product and its method of manufacture. In general, these materials may be tolerated in amounts up to 20 to 25% by weight of the dipropylene glycol coagulant without undue adverse affect on the spinning process. In this connection, it is noteworthy that the amount of such extraneous materials in an operating coagulating bath will diminish after several cycles of recovery and purification of the coagulant by fractional distillation with the result that the coagulating bath will improve in eificiency with use.
• the acrylonitrile polymer employed for the preparation of the spinning solutions may be polyacrylonitrile or copolymers of acrylonitrile containing in the polymer molecule a. major portion of acrylonitrile and with particular advantage over 80% acrylonitrile.
• the spin bath may be maintained at below about 30% by weight ethylene carbonate.
• spin baths containing between about 5 and 25% by weight ethylene carbonate.
• Aqueous washing liquids may be used with advantage and these may consist essentially of water.
• the washing step' may be performed continuously such as by passing the fibers through a water bath or may be performed discontinuously by washing bobbins or cakes of the collected unwashed fibers.
• the washing step may be performed on thread-advancing devices such as pairs of thread-advancing drums or rollers, or on unitary thread-advancmg devices such as reels.
• Particular advantages are derived by washing with aqueous liquids which have been heated to above room temperature such as between about 30 C. and the boiling temperature of the washing liquid.
• the filamentary materials produced .by the method of this invention may be stretched and heat treated so as to produce oriented products having high tenacity, high elastic recovery, low shrinkage, etc.
• Example I 20 parts of polyacrylonitrile (average molecular weight 42,000) was dissolved in 80 parts of ethylene carbonate. This solution, after filtering and deaerating under vacuum, was heated to hours with water at 80 C. The washed yarn was later stretched about 10 times inleiigth while heated to a temperature oi. about 150 C., and thereafter relaxed at a temperature of about 140 C. to produce the final product.
• a quantity of used bath liquid was continually removed from the operating bath and a sufllcient quantity of dipropylene glycol, reclaimed from spent bath liquid as described below, was continually introduced so that the ratio of dipropylenc glycol to ethylene carbonate remained substantially at about 80:20.
• the final yarn product was very light-colored and of uniform quality having a soft, silky feel. a denier of about 94, a breaking tenacity of about 4.4 grams per denier, and a breaking elongation of about 18%.
• the spent bath liquid which was continuously removed from the operating bath was processed and recycled as follows so as to reclaim and reuse both the ethylene carbonate and the dipropylene glycol.
• the removed bath liquid was cooled to about 0 C. to precipitate ethylene carbonate, and the mixture was thereafter rapidly centriiuged to remove the precipitated ethylene carbonate.
• the recovered ethylene carbonate was then recycled for use in the preparation of additional polymeric spinning solutions.
• the mother liquor filtrate was continuously returned to the coagulating bath in controlled quantities, and occasionally, the mother liquor filtrate was distilled at 10 m. m. pressure to remove any impurities or colored matter accumulated in the recycled operating bath.
• CHzC 2 having an average molecular weight of about 50.000. 18 parts of this wpolymer was dissolved in 82 parts of ethylene carbonate and the resulting spinnlng solution was heated to 110 C. betoreextrusion.
• Theoperatingcoagulating bath consisted of a technical grade of dlpropylene glycol and 15% ethylene carbonate and was maintained at a temperature of 110 C.
• the coagulant component in the operating bath, exclusive of ethylene carbonate, consisted 0! approximately 94% dipropylene glycol, 3% tripropylene glycol and 1% propylene glycol and 2% ethylene glycol.
• Example III The procedure of this example is the same as Example I with the exception that the coagulating bath is maintained at about 140 C. and the coagulated filaments are drawn through a bath for about inches of bath travel at a speed of about 150 meters per minute.
• 'copolymers'of .a'crylonitrile with the following monomeric compounds: vinyl esters (vinyl acetate, vinyl iormate, vinyl benzoate) vinyl ethers, and vinyl ketones; acrylic acid and its esters and amides methacrylic acid and its esters, amides, and nitrile; maleic, itaconic, Iumaric crotonic acids and their esters, amides and nitriles: allyl alcohol and its esters; styrene and nuclear substituted styrenes, e. g. chloroand dichloro styrene; halogenated monoethylenic compounds such as vinyl chloride, vinyl fluoride,
• polymers and copolymers are preferably within the range of 10,000 and 250,000, or even higher, although polymers having molecular weights between 30,000 and 150,000 may be used with particular advantage in the production of fibers.
• the spinning solutions may be prepared by heating a mixture of the finely divided acrylonitrile polymer or copolymer with the ethylene carbonate solvent until the polymer is 'dissolved.
• the spinning solution may be maintained, prior to extrusion, at temperatures from about to 150 C., and preferably between about and C.
• These spinning solutions, preferably. should have a from the coagulating bath of the present process may be washed with aqueous media as previously described and then stretched up to 600-1000 percent or more. The stretching may be accomplished in secondary baths containing materials similar to those suitable for use in the coagulating baths of this invention, or if desired, in other heated media such as, for example, inert liquids, vapors or gases, e. g. steam. Steam may be employed both as the aqueous washing medium and also as the heated stretching medium.
• the stretched products may be heat treated while in a relaxed condition at temperatures of between about 100 and 180 C. to improve their physical properties.
• the expression relaxed condition is intended to include the heat treatment of threads and yarns at no tension at all or preferably, at relatively low tensions such as, for example, between about 0.01 and 0.3 gram per denier.
• Oleaginous material such as finishing oils or waxes, may be applied to the yarn and thread products after the heat treating step, or if desired, before the heat treating step.
• the method of forming a shaped article which comprises extruding an acrylonitrile polymer spinning solution containing ethylene carbonate as a solvent into a liquid coagulating medium containing, exclusive of ethylene carbonate, at least about 75% by weight dipropylene glycol; said polymer containing in the polymer molecule a major portion of acrylonitrile.
• a 8 said coagulating medium containing less than about 80% by weight ethylene carbonate.
• the method of forming a fiber which comprises extruding through a spinnaret, an acrylonitrile polymer spinning solution containing ethylene carbonate as a solvent into a liquid coagulating medium containing, exclusive of ethylene carbonate, at least about by weight dipropylene glycol; withdrawing the resulting coagulated filamentary material from the coagulating medium and washing it with an aqueous liquid; said polymer containing in the polymer molecule at least about by weight acrylonitrile.
• the method of forming a fiber which comprises extruding through a spinnaret, an acrylonitrile polymer spinning solution containing ethylene carbonate as a solvent into a liquid coagulating medium which, exclusive of ethylene carbonate, consists essentially of dipropylene lycol, and contains between about 5% and 25% by weight ethylene carbonate; maintaining said coagulating medium at a temperature between about 80 and 150 C.; withdrawing the resulting coagulated filamentary material from said coagulating medium at a speed between about 30 and 200 meters per minute and washing it with a heated aqueous liquid consisting essentially of water; and stretching said washed filamentary material; said polymer containing in the polymer molecule at least about 80% by weight acrylonitrile.

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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 (6)

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Citations (3)

• 0
  • BE BE502217D patent/BE502217A/xx unknown
  • NL NL6810554.A patent/NL160173B/nl unknown
• 1950
  • 1950-04-01 US US153482A patent/US2570201A/en not_active Expired - Lifetime
• 1951
  • 1951-03-28 GB GB7174/51A patent/GB712042A/en not_active Expired
  • 1951-03-30 FR FR1038663D patent/FR1038663A/fr not_active Expired
  • 1951-03-31 CH CH303234D patent/CH303234A/de unknown

Patent Citations (3)

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