US3124629A - Manufacture of shaped objects of acrylonitrile - Google Patents

Manufacture of shaped objects of acrylonitrile Download PDF

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US3124629A
US3124629A US3124629DA US3124629A US 3124629 A US3124629 A US 3124629A US 3124629D A US3124629D A US 3124629DA US 3124629 A US3124629 A US 3124629A
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filaments
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filament
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    • 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
    • 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
    • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/38—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising unsaturated nitriles as the major constituent
    • 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
    • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/40—Modacrylic fibres, i.e. containing 35 to 85% acrylonitrile
    • 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
    • D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/54—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polymers of unsaturated nitriles

Definitions

  • filaments of such polymers are formed by dissolving the polymers in a suitable solvent and then removing the solvent from a flowing stream of the solution to form filaments therefrom.
  • filaments of acrylonitrile polymers are prepared either by the dry spinning process or by the wet spinning process, as is well known. The specific technique chosen results in a compromise among the yarn properties, the economic aspects of the technique involved, and other considerations. There are advantages and disadvantages associated with the employment of each process.
  • the present invention is particularly concerned with the wet spinning process.
  • coagulation is accomplished by extruding the polymer solution into an aqueous bath sometimes containing a percentage of solvent or dissolved salt.
  • an aqueous or water bath refers to a composition having water as one of its main components.
  • the solvent and the bath liquid may interchange in such a manner that the resulting filaments contain voids or cavities along their lengths which can be seen clearly with an optical phase microscope. Filaments containing these voids or unfilled spaces do not possess the requisite physical properties desired for some end uses. For example, such filaments exhibit a delustered appearance, lower tenacity, and lower abrasion resistance as compared with filaments not containing voids.
  • the tenacity of the filaments is improved greatly by various modes of stretching that molecularly orient the polymer molecules but which in addition tend to collapse these voids. To collapse fully these voids the filaments may be dried at rather high temperatures under tension, thereby forming a more dense filamentary structure.
  • the prior art has found that the tenacity of the filaments is satisfactory with such aftertreatment of the filaments. However, tenacity is primarily a longitudinal property of the filaments; and satisfactory tenacity is not the full answer to the attainment of filaments having an optimum balance of properties.
  • abrasion resistance and the resistance to break upon being flexed are most important.
  • Such properties may be regarded as lateral properties as distinguished from longitudinal properties. While drying under tension gives the illusion of forming filaments without voids therein, the voids merely are crushed together. Although the crushed voids do not detract from the longitudinal properties of the filaments to any significant extent, it has been found that lateral stresses cause the filaments to splinter or break. In other words, filaments having voids which are merely crushed together are laterally weak. The art has found that the lateral properties of the filaments can be improved substantially by subjecting the filaments to an annealing operation.
  • annealing procedure includes a series of elevated and reduced pressure treatments applied to the filaments. More specifically, annealing can be accomplished by placing the acrylonitrile polymer filaments in a closed chamber, subjecting them to a high temperature and pressure in the presence of wet steam and then evacuating the chamber. This treating cycle is repeated as many times as needed. It will be appreciated that this annealing operation as just described is expensive and time consuming. Omitting the anneal ing step in the aftertreatment of the Wet spun acrylic filaments results in filaments having a tendency to splinter or fibrillate; and hence, the filaments have a low abrasion resistance. This tendency to fibrillate is minimized by annealing the filaments. The improvement is thought to result from the inter-face surfaces of the collapsed voids being rendered less separable.
  • the polymer lattice has a pattern resembling that of a line, extremely small meshwork, although the interstices are usually somewhat irregular in size and shape.
  • the micropores present in filaments produced by ordinary wet spinning techniques as they leave the coagulating bath are more or less spherical with the polymer lattice defining such interstitial spaces. The distances across these spaces are ordinarily about 250 A. to 3000 A. or greater.
  • the -frequency of occurrence of the micropores in the filaments produced by ordinary wet spinning techniques employing aqueous coagulating baths can be estimated under an electron microscope and is usually 3 590 10 per gram of polymer.
  • the voids that are visible under the optical phase microscope are quite difierent from the micropores or interstitial spaces not visible under an optical phase microscope but readily apparent under an electron microscope.
  • voids as used herein signifies enclosed spaces or surface pits of the filaments which are visible under an optical phase microscope and which do not contain acrylonitrile polymer, whether or not the enclosed spaces contain a fluid or are collapsed.
  • micropore as used herein signifies extremely diminutive enclosed spaces or surface 3 pits of the filaments that are not visible under an optical phase microscope but are visible under an electron m1- croscope and that do not contain acrylonitrile polymer, whether or not the enclosed spaces contain a fluid or are collapsed.
  • these micropores When the freshly spun filaments are stretched, these micropores as would be expected assume the geometric configuration of an ellipsoid. Subsequent collapsing of the porous structure of the filaments due to the presence of these micropores can be accomplished by drying the filaments under tension at an elevated temperature. Annealing the filaments renders the interstitial interface surfaces of the micropores less separable. Hence, annealing is regarded as an important step in the attainment of acceptable lateral physical properties in the filaments.
  • the size and frequency of the interstitial spaces are corre lated with each other so as to produce filaments offering an optimum combination of longitudinal and lateral properties. Therefore, a method is provided whereby the size and frequency of the normally occurring micropores are changed substantially to produce filaments having such properties.
  • Another object is to provide a process for producing such filaments by modification of the conventional acrylonitrile polymer filament forming processes.
  • these objects are accomplished in accordance with the invention by continuously extruding a solution of an acrylonitrile polymer through a desired number of orifices in a spinneret disposed in a liquid medium composed of polyalkylene glycol and continuously directing the thus-formed streams of the solution for a short distance through the medium to coagulate the polymer in the form of filaments.
  • the solvent employed is N,N- dimethylacetamide, N,N-dimethylformamide or the like;
  • the coagulating bath preferably is composed essentially of polyalkylene glycol although during spinning the solvent concentration will build up in the bath with certain concentrations of solvent being completely tolerable. Fresh coagulating bath composition should be supplied to the coagulating bath when the solvent concentration therein becomes excessively high.
  • the solvent is recovered from the bath by conventional methods. Up to at least 20% concentration by weight of solvent can ordinarily be tolerated in the coagulating bath without adversely affecting the filament appearance or properties. Although the coagulating bath is preferably free of water, nevertheless, Water may be present in the coagulating bath n minor amounts without inducing the formation of inferior filaments. For best results, it is necessary to maintain the Water concentration in the coagulating bath below When greater amounts of Water are present 1n the coagulating bath, inferior filaments may be produced.
  • the filaments produced possess advantageous physical properties and differ in structure from other acrylonitrile polymer filaments heretofore known in the art. During their travel from the spinneret to the means used to Withdraw the filaments from the coagulating bath, a stretch may be imparted to the filaments in orderto attenuate same, if desired.
  • the filaments After being removed from the coagulating bath the filaments are stretched to obtain a desired orientation according to various techniques in Order to increase the tenacity, as well as otherwise to improve the physical properties of the filamentary material.
  • the orientation stretch may be accomplished in various ways, it is preferred that the filaments after being withdrawn from the coagulating bath be continuously directed through a second bath and stretched therein.
  • This second bath is preferably composed of hot water; additional solvent remaining in the coagulated filaments is removed therefrom in the second bath.
  • the filaments optionally may be continuously permitted to relax under low tension or in a hot liquid or hot gaseous atmosphere and/or then continuously dried.
  • the filaments may be collected in continuous form or in staple form.
  • various lubricants and other beneficial treating agents may be advantageously placed on the fibers during the manufacturing operation.
  • FIGURE 1 is a side elevation view partly in section showing schematically an apparatus arrangement of a type which can be used in carrying out the process of the present invention
  • FIGURE 2 is a reproduction of a photomicrograph at a magnification of about times of acrylonitrile polymer filaments of textile grade which give the appearance of smooth, glassy rods;
  • FIGURE 3 is a reproduction of a photomicrograph of greater magnification of an acrylonitrile polymer filament that contains numerous voids along the length thereof;
  • FIGURE 4 is a reproduction of a photomicrograph of an acrylonitrile polymer filament substantially free of voids.
  • the present invention provides novel filaments which dilfer markedly from previous wet-spun acrylonitrile polymer filaments.
  • the novel filaments of the present invention are of textile grade quality and are molecularly oriented.
  • textile grade quality refers to the characteristics required of textile filaments, fibers, and the like with respect to strength, elongation, etc. in order that the same can be converted into an acceptable fabric.
  • the filaments also are manufactured from an acrylonitrile polymer and are substantially free of porosity. To be substantially free of porosity means that the density of the filaments closely approaches or corresponds with the density of the acrylonitrile polymer from which the filaments are produced.
  • the filaments are particularly characterized by displaying an internal fiber surface area in the range of about -500 square meters per gram of filament.
  • the inner surface area of the filaments is the total surface area thereof less the geometric external surface area thereof and is measured as described more fully below.
  • the inner surface area is therefore an indication of the number of the micropores in the reticulate filamentary structure. This area is best seen and measured by analyzing a sample of the coagulated filaments as they leave the coagulating bath.
  • the inner surface area is actually a measure of the total area of the engaging sufraces defining collapsed submicroscopie interstitial spaces.
  • the filaments are characterized by having the interstitial spaces spaced apart at a distance of from 10 A. to at most about 300 A. as measured before the filaments are oriented and before said spaces are collapsed.
  • the average diameter of the micropores before orientation and collapsing is 300 A. or less as can be measured visually under an electron microscope.
  • the frequency of the interstitial spaces in the filaments is in the range of about ZOO-2800x10 per gram of filament which can be calculated from internal surface area and diameter data or estimated by visual analysis.
  • the average number of interstitial spaces in the filaments is at least 40,000 per millimeter of length.
  • the filaments may be further characterized by having at least as good and in most instances a higher resistance to abrasion when wet than dry.
  • the novel filaments require a relatively high tension in order to be elongated.
  • a tension of at least one gram per denier has been found to be necessary to elongate a given filament 5 percent in water at 100 F. Comparably high tensions are required at other temperatures to elongate the filaments.
  • the apparent density of the filaments leaving the coagulating bath is unusually high in that they exhibit densities of about 0.7 to almost 1.0 gram per cubic centimeter. Also at this point the filaments have an area ratio of 1.5 to 1.1.
  • ab initio i.e. early in the production of the filaments, some of the conventional aftertreating steps that induce the formation of a denser structure, such as relaxing and annealing described above can be omitted, if desired, without substantial loss of properties.
  • the experimental determination of the isothermal volume of gas adsorbed as a function of pressure gives rise to one of five classical types of isotherms.
  • the shapes of the isotherms are a function of the size of the adsorbing molecule.
  • the gas condenses on the surfaces of the sample whose surface area is being measured and gradually covers the surface as the pressure is increased until a monolayer of gas is adsorbed thereon. Further increases in pressure result in progressive increases in the thickness of the adsorbed layer until at a partial pressure of one, the adsorbed phase is indistinguishable from the liquid phase of the gas.
  • the surface area can be calculated.
  • the advantage of using gas molecules is that the individual gas molecules are small enough to fill the micropores of the novel filaments herein, the diameter of which is only a few angstroms larger than that of the gas molecule.
  • BET Brunauer-Emmett-Teller
  • Equation M is the weight of the molecule
  • N is Avagadros number
  • d is the liquid density.
  • the procedure for determining the surface area per unit weight of filament is to determine volumetrically the amount or" gas adsorbed on the sample as a function of pressure at the temperature the gas liquifies.
  • the amount of gas required to form a monolayer is calculated by the use of the Brunauer-Emmett-Teller equation.
  • the internal surface area of acrylonitrile polymer filaments has been found to be considerable.
  • the ratio of the total surface area to the geometric external area is roughly 500 which indicates a relatively large internal porosity.
  • the density (apparent) of the filaments either as finished filaments or as they leave the coagulating batcan be determined by mercury displacement.
  • the density data indicate the total porosity of the filaments, including the porosity attributable to the presence of voids and micropores.
  • This void volume data, together with the surface area data and diameter data of the micropores, can be used to calculate the size and frequency of the micropores.
  • At least two techniques are known for determining the density of a filament, these being a pycnometer procedure and a buoyancy procedure.
  • the pycnometer method involves determining the volume of mercury excluded from a calibrated pycnometer by a filament sample.
  • the second procedure comprises determining the loss in weight of a calibrated platinum bob in mercury with and without a filament sample. From the data obtained one may calculate conveniently the density of the sample.
  • area ratio refers to the ratio of the measured cross-sectional area of the individual filaments as spun to the cross-sectional area of those filaments as calculated from the denier of the filaments and the known density of the polymer.
  • the filaments prepared in accordance with the present invention possess an unusually low area ratio when the filaments leave the coagulation bath. It is thought that such initially low area ratio is related to the final improved properties of the filaments.
  • acrylonitrile polymer polyacrylonitrile, copolymers, and terpolymers of acrylonitrile, and blends of polyacrylonitrile and copolymers of acrylonitrile with other polymerizable mono-olefinic materials, as well as blends of polyacrylonitrile and such copolymers with small amounts, of other polymeric materials, such as polystyrene.
  • a polymer made from a monomeric mixture of which acrylonitrile is at least 70 percent by weight of the polymerizable content is useful in the practice of the present invention.
  • useful copolymers are those of 80 or more percent of acrylonitrile and one or more percent of other mono-olefinic monomers.
  • Block and graft copolymers of the same general type are within the purview of the invention.
  • Suitable other monomers include vinyl acetate, and other vinyl esters of monocarboxylic acids, vinylidene chloride, vinyl chloride and other vinyl halides, dimethyl fumarate and other dialkyl esters of fumaric acid, dimethyl maleate and other dialkyl esters of maleic acid, methyl acrylate and other alkyl esters of acrylic acid, styrene, and other vinyl-substituted aromatic hydrocarbons, methyl methacrylate and other alkyl esters of methacrylic acid, vinyl-substituted heterocyclic nitrogen ring compounds, such as the vinyl imidazoles, etc., the alkyl-substituted vinylpyridines, vinyl chloroacetate, allyl chloroacetate, methallyl chloroacetate, allyl glycidyl ether, methallyl glycidyl ether, allyl glycid
  • these non-dyeable fiber-forming copolymers may be blended with polymers or copolymers which are in themselves more dye-receptive by reason of their physical structure or by reason of the presence of functional groups chemically reactive with the dyestulf, whereby the dyestutf is permanently bonded to the polymer in a manner which lends resistance to removal thereof by the usual laundering and dry cleaning procedures.
  • Suitable blending polymers may be polyvinylpyridine, polymers of alkyl-substituted vinylpyridine, polymers of other vinyl-substituted N-heterocyclic compounds, the copolymers of the various vinyl-substituted N-heterocyclic compounds and other copolymerizable monomers, particularly acrylonitrile.
  • the polymers just described may be prepared by any conventional polymerization procedure, such as mass polymerization methods, solution polymerization methods, or aqueous emulsion methods.
  • the polymerization is normally catalyzed by known catalysts and is carried out in equipment generally used in the art. However, the
  • the preferred practice utilizes suspension polymerization wherein the polymer is prepared in finely divided form for immediate use in the filament forming operations.
  • the preferred suspension polymerization involves batch procedures, wherein monomers are charged with an aqueous medium containing the necessary catalyst and dispersing agents.
  • a more desirable methods involves the semi-continuous procedure in which the polymerization reactor containing the aqueous medium is charged with the desired monomers gradually throughout the course of the reaction. Entirely continuous methods involving the gradual addition of monomers and the continuous withdrawal of polymer can also be employed.
  • the polymerization is catalyzed by means of watersoluble salts of peroxy acids, sodium peroxide, hydrogen peroxide, sodium perborate, the sodium salts of other peroxy acids, and other water-soluble compounds containing the peroxy group:
  • redox catalyst system A wide variation in the quantity of peroxy compounds is possible. For example, from 0.1 to 3.0 percent by weight of the polymerizable monomer may be used.
  • the socalled redox catalyst system also may be used.
  • Redox agents are generally compounds in a lower valent state which are readily oxidized to the higher valent state under the conditions of reaction. Through the use of this reduction oxidation system, it is possible to obtain polymerization to a substantial extent at lower temperatures than otherwise would be required.
  • Suitable redox agents are sulfur dioxide, the alkali metal and ammonium bisulfites, and sodium formaldehyde sulfoxylate.
  • the catalyst may be charged at the outset of the reaction, or it may be added continuously or in increments throughout the reaction for the purpose of maintaining a more uniform concentration of catalyst in the reaction mass.
  • the latter method is preferred because it tends to make the resultant polymer more uniform in regard to its chemical and physical properties.
  • Suitable reagents for this purpose are the water-soluble salts of fatty acids, such as sodium oleate and potassium stearate, mixtures of water-soluble fatty acid salts, such as common soaps prepared by the saponification of animal and vegetable oils, the amino soaps, such as salts of triethanolamine and dodecylmethylamine, salts of rosin acids and mixtures thereof, the water-soluble salts of half esters of sulfonic acids and long chain aliphatic alcohols, sulfonated hydrocarbons, such as alkyl aryl sulfonates, and any other of a wide variety of wetting agents, which are in general organic compounds containing both hydrophobic and hydrophilic radicals.
  • the quantity of emulsifying agent will depend upon the particular agent selected, the ratio of
  • the emulsion polymerizations are preferably conducted in glass or glass-lined vessels provided with means for agitating the contents therein.
  • rotary stirring devices are the most effective means of insuring the intimate contact of the reagents, but other methods may be successfully employed, for example, by rocking or rotating the reactors.
  • the polymerization equipment generally used is conventional in the art and the adaptation of a particular type of apparatus to the reaction contemplated is within the province of one skilled in the art.
  • the optimum methods of polymerization for preparing fiber-forming acrylonitrile polymers involve the use of polymerization regulators to prevent the formation of polymer units of excessive molecular weight.
  • Suitable regulators are the alkyl and aryl mercaptans, carbon tetra- Time of fiow of polymer solutions in seconds NBD Time of flow of the solvent in seconds 1
  • Viscosity determinations of the polymer solutions and solvent are made by allowing said solutions to flow by gravity at 25 C. through a capillary viscosity tube.
  • a polymer solution containing 0.1 gram of the polymer dissolved in 100 ml. of N,N-dimethylformamide was employed.
  • the most effective polymers for the preparation of filaments are those of uniform physical and chemical properties and of relatively high molecular Weight.
  • a water coagulable solution comprising an acrylonitrile polymer dissolved in N,N-dimethylacetamide, N,N-dimethylformamide, or the like is passed under pressure from a supply tank (not shown) through a conduit 10 and thence through a candle filter 11 wherein undissolved particles and foreign materials in the solution are removed.
  • gear pumps are used to pump the solution through the filter 11 and to meter same to the spinneret assembly 12.
  • This assembly includes a spinneret l3 and is suitably disposed below the upper surface of the coagulating liquid 14 composed primarily of polyalkylene glycol and contained in an open-top spinning trough or bath 15.
  • the solution may be extruded through a single orifice or a plurality of orifices in the spinneret 13 to form a filament or bundle of filaments 16.
  • the extruded streams of polymer are directed through the liquid 14 for a predetermined and sufiicient distance to cause the solution to coagulate as desired.
  • a guide 17 may be employed to define the path taken by the filaments in bath 15.
  • Fresh liquid 14 is supplied to trough through pipe 18 (which may be polyalkylene glycol or polyalkylene glycol containing a desirable quantity of solvent) and is withdrawn therefrom through pipe 20.
  • the coagulated filaments are withdrawn by employment of a positively driven roller 21 or other thread advancing means, the peripheral speed of which preferably is synchronized with the extrusion speed so that the filaments during their travel between the spinneret and the rollers may be attenuated, and if desired, attenuated up to the point just short of where filamentary breakage occurs.
  • the filaments After passing around roller 21 and an idler roll 22, the filaments are directed into a second spinning trough 23 containing a liquid 24. Fresh liquid is supplied to trough 23 through pipe 25 and is withdrawn through pipe 26. While it is quite possible to employ three .or more liquid-containing troughs, only two have been illustrated and described in the interest of simplicity.
  • the filaments before emerging from the liquid in second trough 23 and being directed around a set of positively driven rolls identified by numerals 27 and 28 are passed under guides 30 and 31.
  • the peripheral speed of rollers 27 and 28 can be adjusted so that a predetermined orientation stretch will be imparted to the filaments 16 during their travel in second trough 23.
  • a washing liquid such as hot water is sup plied from a spray or shower head 32, the liquid being collected in a container or tray 33. It will be recognized that the washing operation can be accomplished in more than one stage of the process and by employment of other known washing means.
  • the filaments After leaving rollers 27 and 2d, the filaments are directed through a liquid in a third trough 34 by being passed under guides 35 and 36.
  • the liquid 37 in "this trough is normally water at an elevated temperature.
  • the filaments are withdrawn therefrom by means of a driven roller 38 and associated idle roller 40 operated at a peripheral speed less than that of the peripheral speed of rollers 27 and 28 so that the filaments are permitted to relax substantially completely and thereby to shrink during their travel in trough 34.
  • Fresh water is supplied to trough 34 through an inlet pipe 41 and is withdrawn through an outlet pipe 42.
  • the filaments may be directed around a tapered roller or rollers and progressively led from the end having the larger circumference to the end having the smaller circumference, the rollers being immersed in a liquid or having a liquid applied thereto.
  • the filaments are passed through a finish bath liquid 43 contained in a vessel 44 and composed of a lubricant or fire beneficial treating agent.
  • the filaments after being withdrawn from liquid 43 are dried.
  • the filaments are continuously directed around a pair of driven drying drums 45 and 46 heated internally with steam or the like. Thereafter, the filaments are subjected to additional operations such as crimping, cutting, and then are collected in the form of staple fiber, continuous filament yarn, or tow.
  • the acrylonitrile polymer selected is dissolved in N,N-dimethylacetamide, N,N-dimethylformamide or the like to form a spinning solution.
  • This solution is extruded through a spinneret into a coagulating bath composed of polyalkylene glycol.
  • polyalkylene glycol refers to polyethers which may be derived from alkylene oxides or glycols or from other heterocyclic ethers such as dioxolane, and which may be represented by the formula HO.(RO),,H in which R stands for an alkylene radical such as methylene, ethylene, propylene, etc., and n is an integer of at least four.
  • R stands for an alkylene radical such as methylene, ethylene, propylene, etc.
  • n is an integer of at least four.
  • the polyglycol may contain inert substituents; for example, methoxypolyethylene glycol may be employed. Not all of the alkylene radicals present need be the same.
  • glycols containing a mixture of radicals such as in block polymers and copolymers are also useful.
  • mixtures of polyglycols of difiering compositions or molecular weights can be employed.
  • the glycols which are useful in the process of this invention have molecular weights of at least 200 and may have molecular weights as high as 6000.
  • the preferred glycols are the polyethylene glycols which preferably have molecular weights of 6002000. These glycols as just defined are either viscous liquids or waxy solids at room temperature. However, they become less viscous at higher temperatures and permit spinning at these temperatures. Although wide variations in the spin bath temperatures are permitted, it is preferred that the temperatures be of the order of 50 to 150 C. depending on which glycol is employed.
  • FIGURE 2 is a drawing prepared from a photomicrograph. This illustrates the normal appearance of acrylouitrile polymer filaments heretofore known at a magnification of times. At this magnification no visible difierences between the filaments of the present invention and the known filament are noticeable since the voids or cavities on the surfaces of the filaments are not apparent.
  • FIGURE 3 is a drawing prepared from a photomicrograph showing a view of part of a filament containing voids or cavities. Enclosed voids of the filament also can be seen by observing a cross section of the filament. Due to the presence of the voids, the light rays impinging thereon are scattered, imparting a dull subdued luster to the filament.
  • FIGURE 4 is a drawing prepared from a photomicrograph showing a corresponding view of part of a filament substantially free of voids or cavities. Due to the substantial absence of voids, the filament has a lustrous appearance.
  • the novel filaments of the present invention are substantially free of voids and hence have a normally lustrous appearance. However, when desired, delustrants, pigments, and the like can be incorporated in the filaments to produce dull or colored products.
  • the marked differences of the novel filament herein and those heretofore known become apparent when the comparison of the reticulate filamentary structures is made at magnifications obtainable by the use of an electron microscope.
  • the spinning solution can be prepared by heating and stirring a mixture of a finely divided acrylonitrile polymer of the type described above with a solvent selected from the group consisting of N,N-dimethylacetamide, N,N-dimethylformamide, or the like.
  • a solvent selected from the group consisting of N,N-dimethylacetamide, N,N-dimethylformamide, or the like.
  • the percentage of polymer based on the weight of the solution depends upon the particular polymer or solvent employed as well as the temperature at which the polymer is spun. It is desirable to employ a solution containing a high percentage of polymer for obvious reasons. Ordinarily a solution containing at least percent acrylonitrile is desirable.
  • the spinning solution may be maintained prior to and at extrusion at temperatures from about 20 to 150 C.
  • the coagulating bath contributes to the formation of the improved fiber structure, it is believed that the relatively large size of the polyalkylene glycol molecules is such that inflow thereof into the coagulating filaments is minimized whereby denser and more compact filaments are obtained.
  • Filaments may be given a travel in the coagulating bath, for example, from 2 to 24 inches or more by the employment of a suitably spaced guide and withdrawal rolls as illustrated in FIGURE 1. Between the spinneret and withdrawal rolls, the filaments as indicated above may be subjected to a stretching operation to obtain a desired attenuation thereof, if desired.
  • a second bath is employed following the coagulating bath wherein the filaments are given a stretch in order to increase the strength as well as otherwise to improve the physical properties of the filaments. This improvement results from an orientation of the polymer molecules along the filament axis.
  • the second bath may consist simply of water, or it may have the same composition as the coagulating bath but at a greater dilution with water.
  • the temperature of the second bath is preferably between 50 and 100 (3., the highest feasible temperature being preferred. Draw ratios up to 10 or higher may be employed; the amount of'stretch applied depends on the properties desired for the yarn. Preferred draw ratios lie between 1.5 and 8.0.
  • the filaments are washed substantially free of solvent if desired. This may be accomplished by spraying water on the filaments traveling around positively driven rolls. The water extracts the solvent from the filaments as they pass gradually from one end of the rollers to the other end. Other equivalent washing means, of course, can be used. Moreover, the washing can be carried out prior to applying the orientation stretch to the filaments as indicated above.
  • the filaments may be permitted to relax, if desired.
  • the resulting filaments which are relaxed in hot or boiling water have higher elongation values as compared to filaments produced in a comparable manner but without being permitted to relax.
  • the higher elongation values are obtained without a sacrifice of tenacity.
  • an inverse relationship exists between the elongation of the resulting filaments and the temperature at which the filaments are given the orientation stretch. That is to say, for a given orientation stretch, filaments having higher elongation are obtained generally where lower stretch temperatures are employed.
  • the step of relaxing is not entirely necessary in accordance with the present invention although in some cases it is to be recommended.
  • the filaments are dried in a conventional manner. This may be done either under tension or under no tension.
  • the filaments produced by the present invention after leaving the relaxation bath have a substantially reduced porosity and have a smooth mirrorlike surface.
  • the disadvantages associated with drying under tension such as yellowing of the filaments when subjected to high local temperatures on the drying drums and like apparatus used in a tension drying operation, may be avoided and yet produce filaments having a luster greater than normal wet-spun filaments dried under tension.
  • the present process enables one to produce filaments of very fine deniers. Owing to the high jet stretch permitted by the process as pointed out above, filaments having individual filaments as low as 0.25 can be successfully spun.
  • EXAMPLE I A 20 percent solution of a copolymer of percent acrylonitrile and 5 percent vinyl acetate was prepared by intimately mixing the copolymer in powdered form with the solvent, N,N-dimethylacetamide, until a clear liquid resulted. The resulting solution was cooled to a temperature of 50 C., filtered, and extruded through a spinneret submerged in a coagulating bath composed of polyethylene glycol having an average molecular Weight of 1000. The filaments so formed were withdrawn from the coagulating bath after a travel therein of 20 inches and thereafter directed through a bath of boiling water where a stretch of 6.0 times was imparted to the filaments.
  • the filaments were dried by passing same around rotating drying cans maintained at a temperature of C. Samples of the filaments were taken at the point where they emerged from the coagulating bath and were centrifuged for 60 seconds to remove excess surface liquids. Analyses for several typical samples are presented below in Table 1. Additional spinnings were conducted using polyethylene glycol having a molecular weight of 600 as the coagulating liquid. This lower molecular weight glycol was employed in the presence of varying amounts of the dimethylacetamide solvent. Also, filaments were produced using an aqueous coagulating bath having the composition of 55 percent N,N-dimethylacetamide and 45 percent water. The results of these spinnings are also given in Table 1.
  • Bath Yarn appear- Max. Bath Composition Temp, ance Jet C. Stretch There appears to be a general increase in maximum jet stretch as a function of temperature.
  • temperature and not bath composition appears to be the important variable
  • the effect of bath composition is additive with the thermal eifect to give higher stretches with increasing molecular weight at a given temperature.
  • An opaque appearance of the yarn indicates an internal spongy structure whereas a clear appearance indicates a denser, more homogeneous structure.
  • the typical cross section of yarn spun into the polyethylene glycol bath is somewhat in the shape of a horseshoe, and the filament is suggestive of a fiat ribbon which has been rolled lengthwise until its edges nearly meet.
  • the maximum afterstretch obtainable for the polymer solutions spun in the polymeric glycol bath was in the range of from 7.5 to 10 times and on the average, 8.5 times.
  • the same polymer solution spun in solvent/ water mixtures generally gave a maximum afterstretch of less than 7.0 times regardless of bath temperature or solvent-water ratio. This shows that the filamentary structures obtained by the use of the glycol bath are capable of accepting higher stretches than can normally be obtained by employing aqueous coagulating baths.
  • EXAMPLE III A 20 percent solution of the copolymer of 95 percent acrylonitrile and 5 percent vinyl acetate in N,N-dimethylacetamide was prepared and extruded into coagulating baths composed of polyethylene glycol of 1000 and 4000 molecular weights to determine the effect of the baths on spinning speeds and denier range.
  • EXAMPLE IV The acrylonitrile polymer solution of Example III was spun into a coagulating bath composed of equal parts of mixed polyethylene glycols having molecular weights of 400 and 1000. A portion of the resulting filaments were passed through a bath containing a yarn lubricant and an anti-static agent; filaments which had not been so treated compared favorably therewith. It was found that even without the application of finish the filaments have a soft, pleasant hand and required only the application of antistatic finish to give satisfactory processability into fabric.
  • EXAMPLE V A series of spinnings were conducted in which a 20 percent solution of the copolymer of 95 percent acrylonitrile and 5 percent vinyl acetate in N,N-dimethylacetamide was extruded in various coagulating baths as indicated below in Table 3. The values of tenacity and elongation for various fibers spun in the glycol baths, together with data of comparative controls spun in aqueous baths, are also given in the table.
  • filaments spun into the polymeric glycol baths generally show higher values for both elongation and tenacity than the aqueous controls. It is also appar cut that the filaments spun into the polymeric glycol baths have a better balance of elongation and tenacity than do the controls.
  • EXAMPLE VI The acrylonitrile polymer solution of Example III was spun into a coagulating bath composed of polyethylene glycol having an average molecular weight of 4000. The resulting filaments were processed as in Example I with an afterstretch of 7.0 times being imparted to the filaments. The finished filaments had deniers ranging from 4-9 with tenacities of 2.7-3.2 g./den. and elongations of 1727 percent.
  • EXAMPLE VII A homopolymer of acrylonitrile was dissolved in N,N- dimethylformamide to form an 18 percent solution of the polymer. The resulting solution was spun into a bath containing polyethylene glycol having an average molecular weight of 1000. Samples were collected with a variety of afterstretches and had physical properties as given The acrylonitrile polymer solution of Example III was extruded in a series of coagulating baths composed of polypropylene glycol of varying molecular weight. The results of these spinnings are summarized in Table 5 below.
  • Example III The acrylonitrile polymer solution of Example III was spun into a coagulating bath at 90 C. containing methoxypolyethylene glycol having an average molecular weight of 750. The resulting filaments were aftertreated as in Example I with afterstretches of 4-6 times. The finished filaments had tenacities of 34 g./ den. and elongations of 2030 percent.
  • EXAMPLE X Eighty-eight parts of a copolymer of 95 percent acrylonitrile and 5 percent vinyl acetate were blended with 12 parts of polyvinylpyrrolidone with the resulting blend being dissolved in N,N-dimethylacetamide to form a 20 percent solution. This solution was extruded into a bath composed of polyethylene glycol having an average molecular weight of 1000. The resulting filaments were processed in the manner described in Example I with an afterstretch of 6 times being imparted to the filaments.
  • the finished filaments contained in excess of 10 percent polyvinylpyrrolidone and had improved dye takeup with most dyestuffs.
  • the filaments had a tenacity of 3.9 g./ den. and an elongation of 21 percent.
  • a spinning solution was prepared by dissolving a copolymer of 94 weight percent acrylonitrile and 6 weight percent of vinyl acetate in N,N-dimethylacetamide.
  • Samples of the spinning solution at 30 C. were extruded through a spinneret into a coagulating bath consisting essentially of polyethylene glycol having a molecular Weight of 1000 and maintained at 93 C.
  • the filaments were withdrawn from the coagulating bath after the same were directed therethrough for a distance of 24 inches. At this point it was found that the filaments were composed of 42.2 percent acrylonitrile polymer, 9.2 percent N,N- dimethylacetamide, and 48.6 percent of polyethylene glycol.
  • the filaments were then passed through a water wash bath. It was found that the filaments were composed of 47.6 percent acrylonitrile polymer, 2.1 percent N,N-dimethylacetamide, and 50.3 percent water.
  • the same acrylonitrile polymer spinning solution was likewise extruded into an aqueous coagulating bath composed of 55 percent N,N-dimethylacetamide and 45 percent water at 50 C.
  • the filaments removed from the coagulating bath in this instance were composed of 28.7 percent acrylonitrile polymer, 40.0 percent N,N-dimethylacetamide and 31.3 percent water.
  • the filaments were then passed through a water wash bath as above. It was found that the filaments were composed of 26.9 percent acrylonitrile polymer, 0.0- ⁇ - percent N,N-dimethylacetamide, and 73.1 percent water.
  • a spinning solution was prepared by dissolving in N,N- dimethylacetamide a blend of (A) a copolymer of 97 percent acrylonitrile and 3 percent vinyl acetate with (B) a copolymer of 50 percent acrylonitrile and 50 percent 2-methyl-5-vinylpyridine, said blend containing 6 percent vinylpyridine based on the weight of the blend.
  • the polymer blend had a specific viscosity of 0.25 and the spinning solution contained 18 percent solids.
  • the solution was extruded at 50 C. through a spinneret contain ing 1000 holes, each being 0.003 inch in diameter, into a coagulating bath composed essentially of polyethylene glycol having a molecular weight of 1000.
  • the temperature of the coagulating bath was maintained at 100 C.
  • the bundle of filaments formed was led through the bath for a distance of 36 inches and then was removed therefrom at a rate of 40 feet per minute, the rate of withdrawal being established in relation to the rate of extrusion so that the filaments are subjected to a draw ratio of 1.1 between the spinneret submerged in the coagulating bath and the means used to withdraw the filaments from the coagulating bath.
  • the filaments were passed into a second stretch bath maintained at 100 C. and containing essentially water. After they had traveled a distance of 12 inches in the second bath, the filaments were withdrawn at a rate of feet per minute so that a stretch of approximately 3.5 times was imparted to the filaments.
  • the filaments were then passed around a pair 1 7 of spaced apart rollers 30 to 40 times with a total length of filaments around the rollers at one time being about 120 feet. Water at 5080 C. was sprayed on the filaments during their travel around said rolls to washsame.
  • the filaments were dried by being passed around a heated drum assembly.
  • polymer spinning solution was spun into aqueous'coagulating bath having the composition of 5 5 percent.N,N-dimethylacetamide (DMA) and 45 percent water. This bath was maintained at 55 C.
  • the filaments were given an orientation stretchof .45 .timesand subjected to an annealing operation as above described.
  • Th6;P1 6 cnt invention makes possible the production of acrylonitrile polymer filaments that have an optimum .balaneeof longitudinal and lateral properties and that are eminently suitable for use in the textile art.
  • the filaments have increased elongation realized without sacrifice of tenacity, higher elongation enabling the filaments to be tougher and to be able to adsorb more energy without breakage.
  • the filaments are substantially free from voids and have a highly lustrous appearance. By proper selection of stretch ratios, it is possible according to the present invention to produce a filament equivalent in elongation-tenacity balance to the normally aqueous spun filaments that have been annealed.
  • the annealing step may be eliminated without sacrificing the physical properties of the yarn in regard to balance of elongation and tenacity. It is not necessary according to the present invention to dry the filaments under tension in order to produce a satisfactorily dense fiber structure. Also the present process lends itself readily to employment on a commercial scale without substantial modification of conventional equipment.
  • the surface of filaments spun into a high molecular weight polyalkylene glycol bath of the present invention is relatively smooth and substantially free from the surface pits which characterize filaments spun in aqueous baths. The smooth surface of the filaments results in a very high gloss.
  • a delustrant such as titanium dioxide, opaques the filaments but does not mask the surface gloss. Boiling or annealing usually has little affect on the appearance of the filaments.
  • a process for producing a filament from an acrylo nitrile polymer which comprises dissolving said polymer in a solvent selected from the group consisting of N,N-dimethylacetamide and N,N-dimethylformamide, extruding the resulting solution through a shaped orifice immersed in a coagulating bath consisting essentially of polyalkylene glycol having a molecular weight of 2006000, less than 10 percent water, and up to 20 percent of the selected solvent, thereby precipitating said polymer from its solution in the form of a filament, withdrawing said filament from said coagulating bath, stretching said filament to a substantial extent, and drying said filament, whereby a dense filament having a smooth surface is formed.
  • a solvent selected from the group consisting of N,N-dimethylacetamide and N,N-dimethylformamide
  • a process for producing a filament from an acrylonitrilc polymer which comprises the steps of preparing a V spinning solution containing said polymer by dissolving said polymer into a solvent selected from the group consisting of N,N-dimethylacetamide and N,N-dimethylformamide, extruding the resulting solution into a stream by forcing said solution through an orifice of a spinneret dis- 4 posed in a coagulating bath composed essentially of polyalkylene glycol having a molecular weight of 200-6000, less than 10 percent water and up to 20 percent of the selected solvent, stretching the thus-formed filament between the face of the spinneret and the point of withdrawal from the coagulating bath to attenuate same, withdrawing the thus-formed filament from the coagulating bath, passing the filament through a hot water bath and stretching same in the presence of the hot water to orient 2Q molecules thereof, Washing said filament by contacting it with Water, and thereafter drying and collecting the filament.
  • a solvent selected from the group consist

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  • Chemical & Material Sciences (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
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US3124629D 1958-08-18 Manufacture of shaped objects of acrylonitrile Expired - Lifetime US3124629A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3240745A (en) * 1961-10-20 1966-03-15 Monsanto Co Viscosity control of acrylonitrile polymer solutions
US3246067A (en) * 1962-05-14 1966-04-12 Du Pont Wet-spinning of aromatic polyester filament of high opacity
US3619453A (en) * 1969-11-03 1971-11-09 Celanese Corp Wet spinning process for the production of polybenzimidazole filaments
US4075075A (en) * 1970-04-22 1978-02-21 Japan Atomic Energy Research Institute Process for preparing novel synthetic fibers
US4883628A (en) * 1983-12-05 1989-11-28 Allied-Signal Inc. Method for preparing tenacity and modulus polyacrylonitrile fiber
US5911930A (en) * 1997-08-25 1999-06-15 Monsanto Company Solvent spinning of fibers containing an intrinsically conductive polymer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0244388A3 (en) * 1986-04-03 1989-08-23 Monsanto Company Acrylic fibers having superior abrasion/fatigue resistance
CN116657267B (zh) * 2023-06-01 2025-07-25 山东大学 一种提高聚丙烯腈初生纤维的结晶度以及均质化和致密化程度的方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2570200A (en) * 1949-06-13 1951-10-09 Ind Rayon Corp Wet extrusion of acrylonitrile polymers
US2761754A (en) * 1952-06-07 1956-09-04 Celanese Corp Process for the production of acrylonitrile polymer fibers
DE1085645B (de) * 1959-05-06 1960-07-21 Hans J Zimmer Verfahrenstechni Verfahren zur Herstellung von Polyacrylnitrilfaeden oder -fasern mit hoher Festigkeit
US2967086A (en) * 1957-05-29 1961-01-03 Stockholm Superfosfat Fabriks Process of wet-spinning fibers containing polyacrylonitrile

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2570200A (en) * 1949-06-13 1951-10-09 Ind Rayon Corp Wet extrusion of acrylonitrile polymers
US2761754A (en) * 1952-06-07 1956-09-04 Celanese Corp Process for the production of acrylonitrile polymer fibers
US2967086A (en) * 1957-05-29 1961-01-03 Stockholm Superfosfat Fabriks Process of wet-spinning fibers containing polyacrylonitrile
DE1085645B (de) * 1959-05-06 1960-07-21 Hans J Zimmer Verfahrenstechni Verfahren zur Herstellung von Polyacrylnitrilfaeden oder -fasern mit hoher Festigkeit

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3240745A (en) * 1961-10-20 1966-03-15 Monsanto Co Viscosity control of acrylonitrile polymer solutions
US3246067A (en) * 1962-05-14 1966-04-12 Du Pont Wet-spinning of aromatic polyester filament of high opacity
US3619453A (en) * 1969-11-03 1971-11-09 Celanese Corp Wet spinning process for the production of polybenzimidazole filaments
US4075075A (en) * 1970-04-22 1978-02-21 Japan Atomic Energy Research Institute Process for preparing novel synthetic fibers
US4883628A (en) * 1983-12-05 1989-11-28 Allied-Signal Inc. Method for preparing tenacity and modulus polyacrylonitrile fiber
US5911930A (en) * 1997-08-25 1999-06-15 Monsanto Company Solvent spinning of fibers containing an intrinsically conductive polymer
US6127033A (en) * 1997-08-25 2000-10-03 Kinlen; Patrick J. Solvent spinning of fibers containing an intrinsically conductive polymer

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NL242430A (enrdf_load_stackoverflow)
NL259702A (enrdf_load_stackoverflow)
SE305922B (enrdf_load_stackoverflow) 1968-11-11
FR1233856A (fr) 1960-10-12
GB888342A (en) 1962-01-31
CH384775A (fr) 1965-02-26
GB977943A (en) 1964-12-16
DE1469045A1 (de) 1968-12-05

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