US2611929A - Method of producing shaped articles from artificial or synthetic fiberor film-forming materials - Google Patents

Description

Sept. 30, 1952 HOXlE 2,611,929 METHOD OF PRODUCING SHAPED ARTICLES FROM ARTIFICIAL 9 0R SYNTHETIC FIBER OR FILM-FORMING MATERIALS Filed June 18, 1951 INVENTOR. HOWARD M HOX/E ATTORN r.

' cipitant, or with a mixture of the Patented Sept. 30, 1952 METHOD OF PRODUCING SHAPED ARTICLES FROM ARTIFICIAL R SYNTHETIC FIBER- OR FILM-FORMING MATERIALS Howard M. Hoxie, Chester, Pa., assignor, by mesne assignments, to The Ohemstrand Corporation,

Decatur, Ala., a corporation of Delaware Application June 18, 1951, Serial No. 232,208

This invention relates to improvements in the production of synthetic or artificial fibers, films, or other shaped articles by the wet-spinning or wet-forming processes.

This application is a continuation-in-part of my application Serial No. 125,679 filed November 5, 1949, issued as Patent Number 2,577,763, De-

cember 11, 1951.

I In wet-spinning or wet-forming, as conventionally practiced, a solution of the material to be shaped is extruded into a vessel containing a suitabl setting liquid which is continuously or periodically withdrawn from the vessel, reconditioned, and returned to the extrusion vessel.

I In making shaped articles from fiberor filmmethylformamide solution of the polymer into a setting bath consisting of water and dimethylformamide in controlled predetermined proportions, as disclosed in my pending application Serial No. 62,413, filed November 27, 1948.

I The present invention is concerned more particularly with wet-spinning or wet-forming proc esses in which a solution or dispersion of the fiberor film-forming material is extruded into a setting bath comprising the solvent and a precipitant in critical, controlled relative proportions which must be maintained throughout the extrusion, and has as one object to facilitate maintaining the relative proportion of solvent to precipitant in the setting bath substantially constant from the beginning to the end of the extrusion.

In accordance with the invention, a solution or dispersion of the fiberor film-forming materialis extruded into a setting bath comprising the predetermined proportion of solvent and precipitant to form the shaped article, the article is withdrawn from the bath and, prior to any drying thereof, it is washed with the preprecipitant and a minor proportion of the solvent, and liquid from this initial washing of the article is continuously delivered to the setting bath. The

constituents of the liquid from the washing step 14 Claims. (01. 18-54) or to depend on periodic or stances including vinyl acetate, styrene,'j

. 2 i; are the same as the constituents of the setting bath, and by correlating the proportion of precipitant to solvent in the liquid from the wash-v ing and the rate of flow of such liquid'into'l the setting bath with the amount of solventiritroduced into the bath by the solution of the material to be shaped, the composition of thebath may be maintained constant. Thereforefwhen operating in accordance with the invention, it is unnecessary to withdraw the setting'bath'irom the vessel in which the extrusion is performed,

hap-hazard additions of either solvent or precipitant to thegbath in order to maintain the composition of the bath constant. The method of the invention can be, used for producing artificial or synthetic fibers or other shaped articles from any fiberorfilm forming material which can bedissolved 0r dispersed and wet-spun, when the shaping involves'precipitation only. Examples of suitable fiberand filmforming materials are the organic acid esters of cellulose, the-fiber-forming synthetic resins: including polyamides, polyesters, fiber=forining vinyl resins, polyvinyl alcohol, and fibeIrIQfming polymers of acrylonitrile. The solvent or dispersing agents selectedfwill depend on the particular fiberor film-forming material to be shaped. As examples of suitable solvents or dispersing agents may be mentioned, acetone for commerciaLsecondary, cellulose acetate and such fiber-forming vinyl resins as those resulting from the. conjoint polymerization of vinyl chloride and vinyl acetate or of vinyl "chloride and acrylonitrile and containing from' 40 to acrylonitrile in the molecule; hot-phenol 0r formamide ior polyamides; chloroform for the polyesters; and dimethylformamide, dirnethylacetamide or dimethylpropionamide for acrylonitrile polymers containing from '70 to 98% by weight of acrylonitrile in the molecule and obtaiinedby polymerizing acrylonitrile with one or moref'other monethylenically unsaturated polymerizabl subinyl chloride, vinyl monomers containing bas'i, tertiary nitrogen such as the vinylp'yridi'nes and particularly the 2-vinylpyridines, 5-vinyl"2- methylpyridine and the like, isobutene, "dimethylfumarate, methylmethacrylate, methacrylonitrile and acrylic acid and its esters. The solvent "and dispersing agents mentioned are illustrativejfonly and other solvents or dispersing agents maybe substituted for them. I The precipitant selected will depend on both 5o the'fiberor film-forming material being shaped such material is dissolved or dispersed. It may be any liquid which is an extractive for the extrusion solvent or dispersing agent but inert to 4 fibers advance upwardly through the trough 6, they are washed by liquid supplied to the trough from the vessel 9 with which the trough communicates, for example, with water which may the fiber-.formingmaterial. ..When water meets 5 be heated to a temperature up to 100 C., for tnis essential requirement, water is the preferred instance: from room temperature: to 100 C. precipitant for use in the setting bath and as The liquid precipitant for the washing, or the the major component of the Washing liquid to .mixture of the precipitant with a minor prowhich the fibers or the like are subjected imme- "portion of solvent, is metered into vessel 9 diately after their withdrawal from th'e bath. 10". through pipe lil'provided with valve II, and A specific embodiment of theinvention 'convessels is provided with a vertically adjustable templates the production of fibers or threads from overflow pipe [2. for adjusting the level of the solutions or dispersions ofacrylonitrile polymers ,liquid in vessel 9 to thereby adjust or control the containing, by weight in the polymer molecule, at .quantity of precipitant or of precipitant-solvent least 70% of acrylonitrile, in dimethylacetamide, vmixture delivered to the trough. The liquid flows by spinning the solution into a setting medium downwardly through the trough countercurrently consisting of water and a controlled proportion to-the'direction of the fibers and is collected in of dimethylacetamide. In a preferred embodithe vessel l3 supported adjacent to vessel 2 conment, a solution of the acrylonitrile polymer in 'taining the setting bath. A controlled portion of .....dimethylacetamide is continuously extruded into that liquid, which always comprises a mixture .asetting bath comprising a mixture of water and of the precipitant and the solvent, is continujdiniethyla'cetamide. containing the dimethylously delivered to-vessel 2 through'pipe" 14 pro- Uacetamide in a selected. proportion. between 20 vided with valve I5, the rate of flow be ng conand' 70 by .volume, and the composition of the trolled and correlated with the proportion of solsetting-bath is maintained'constant by'washing vent in the bath so that the liquid introduced the fibers as they are withdrawn from the bath from vessel I3'serves to compensate for the p ewith water onwater :containing a minor propor- 'cipitant and'solvent carried from the bath by the ii tion of dimethylace'tamide, and delivering the fr hly f rmed fi r n hi W y, h r l tive 1 liquid fromthe washing step into the setting proportions of the precipitant and solvent in the bath at acontrolled rate. I .The conditions are setting'bath' are maintained substantially con- .selected so that the composition of the setting Stantb'ath-does notvary more than 2% from the pre- V ss l 2 is provid dwith an overflow p p 6 ;.-.determined volumetric proportions and the proformaintainingthe level of the setting bath conportion of dimethylacetamide present in' the stantpand avertically adjustable overflow pipe setting bath is at least 20% by volume. H associated with vessel [3 permits withdrawal .'.--.At the start of operations under any given set I of any liquid fr m th wash n st p which is'not Iofspinning conditions, the proportion of precipidelivered to vessel 21 The withdrawn liquid may ...tant to solvent required in the liquid from the be stored for lateruse as a setting bath.

washing step and the rate at which that liquid -When the spinning is conducted at room tem- ..must be delivered to the setting bath to maintain 40" perature, as is preferred, or at temperatures begtheicomposition of thebath constant, can be delow 100 C., and the washing liquid is heated, it ..termined byobservation of the-refractive index of is necessary to cool the liquid from h Washing Lathe bath; Thereafter, adjustments in the washstep-before delivering it to the bath. This may ing conditions and in the rate at which the wash be accomplished by associating anysuit'able coolliquid is delivered to the bath .are generally not ins-means, for example, a cooling'coil ill, with wrequired so long as the spinning conditions are vessel 13 as shown, through which a cooling fiuid not changed; However, if such adjustments are is c r ul t d o a just the temp t e -1iequired,.they may be made simply by increasing liquid collected in vessel I 3 to the temperature Con-decreasingthe. rate of flow of the. washing of the-spinning bath before it enters vessel 2. .1i'quid tethe washing zone, and/or by increasing 5O An' advantage of the present method is that the avoridecreasing the rate of fiow of the liquid from gtheewashing step to the setting bath. Suitable F apparatus .for the production of artificial or syn- N. thetic fibers or. threads in accordance with: the invention is illustrated. in the. accompanying spinning solvent is recovered from-mixtures in which it is present in'relatively-high concentration i. e., from the settirig bath or from liquid remaining after initial washing of the fibers or the like.

.,. drawing in which the single figure is a diagram- .e.matic,-. perspective view of a preferred embodi- ;.ment of the invention.

-.cReferring tothe drawing, the solution of the If the washing liquid is a mixture of the precipitant'and'solvent, the proportion of solvent present therein must be controlled and should not be greater than one-half the amount of solvent present in the setting bath.

If it is desired to stretch the'article for orientation,-the article may be stretched prior to, during, or after the initial washing at temperatures desfibereforming. material is extruded through the 0,, .spinneretl into vessel2 containing a settingbath scomprisingthe predetermined. relative proporevtionsof solvent" and precipitant; .The fibers are withdrawn from the bath under the guide 3 and ,lapped-around godet 4, a thread displacing guide 5 .being ,supportedadjacentthe godet. .From

godet 4; the fibers are passed upwardly through the. open'trough 6 and lapped around godet 1, a

Z""'threaddisplacing guide 8 beingsupportedadja- --pehding on the material shaped, and may or may not be given an" after-stretch. For example,

" freshly-formed'fibers' of the acrylonitrile poly- -mers o1" blends'may be stretched'IOO to-300%-at temperatures up to' 100 stretched morethan 300% 0., or they may be at temperatures above cent to that godet to assist in laying the fibers.

.' ;As shown, godets 4 and 1 are of the same size 100 0., and such stretching may be the only stretch'given the-fibers. Or the fibers may be and may be driven at different peripheral speeds stretched-up to' 200 chi-300% attemperatures of i to stretch the fibers. If desired, godets 4 and 1 "100 0;, "a after-stretched tt mperatures may betof. difier'ent'sizes and driven at the same above-100 0:; the after-stretching beingper- "speed" to accomplish the stretching. As the formed either before or =after'final drying of the fibers. In {the 'embodimentillustrated on the drawing-the acrylonitrile polymer fibers may be I stretched between "the godets' 4 and 1 simultaneously with washing thereof with water at any temperature up to 100 C., for instance a temperature between ordinary room temperature and 100 0., v and then after-stretched at temperatures above l-' C. If the acrylonitrile polymer fibers are to be simultaneously stretched and heated to a temperature above 100 C., the godet used in-the production of shaped article's, espe- -cially fibers of the acrylonitrile polymers, which term is intended to include polyacrylonitrile, co-

polymers and interpolymers of a'crylonitrile with one or more other vinyl type monomers contain-. 1 ing at least 70% of acrylonitrile by weight in the polymer molecule, and blends comprising the acrylonitrile polymers. Examplesof the latter are those compositions obtained byblending an acrylonitrile' polymer containing, by weight in the molecule at least 70% of acrylonitrile with a copolymer of from to 70% of acrylonitrile and from'30 to 90% of a'yinyl-substituted heterocyclic tertiary amine, such as a vinylpyridine'to obtain a blend having an overall content'of the poly:

merized vinyl-substituted tertiary heterocyclic amine of from 2 to 50%, based ontheweight of -.i th'eblend. I The following examples illustrate a specific embodiment ofx'the invention:

Emamplel Using apparatus as shown in the drawing, a

' 3000 filament tow was formed by continuously extruding a spinning solution comprising a homo: geneous mixture of N,N-dimethylacetamide and 14.2% by weight of a polymer containing about 95% of acrylonitrile and about 5% of 2-vinylpyridine throughaspinneret into a setting bath at room temperature and consisting of 58% of N,N-dimethylacetamide and 42% of water, by weight, the solution being delivered through the spinneret at a rate of 1.76 lbs/minute. The tow of filaments carried 0.5 lb. of N,N-dimethylacetamide per minute out of the setting bath into the trough 6. Water at about 100 C. was delivered to the trough at a rate of a gallon (8.33 lbs.) per minute. The liquid from the washing was collected in vessel 13, in which it was cooled to room temperature. From vessel l3 the liquid was continuously delivered to the bath in vessel 2 at a rate of 0.146 gallon (1.21 lbs.) per minute. Under these conditions, the composition of the setting bath remained at 58% of N,N-dimethylacetamide and 42% of water from the beginning to the end of the spinning which was, performed continuously over a period of eight hours.

Example II Using apparatus as shown in the drawing, a 5000 filament tow was formed by continuously extruding a spinning solution comprising a. homogeneous mixture of N,N-dimethylacetamide and 14.2% of a copolymer of 95% acrylonitrile and 5% of 2-vinylpyridine, at room temperature and consisting of 58% of N,N-dimethylacetamide and 42% of water, by weight, the solution being delivered through the spinneret at a rate of 2.937 lbs. per minute. The tow of filaments carried 0.834 lb. of N,N-dimethylacetamide per minute from the setting baths; into trough .6.- waterat about 100 C. was delivered to .the trough 1mm i vessel 9 at a rateroi one gallon'l(8.38 lbs.)rper minute. The water from the washing which consisted of water and 9.12% of N,N dimethylacetamide, was collected'in vessel l3, in which it was cooledto room temperature by the cooling fluid circulatingin coil l8, and from which it was continuously delivered to the bath in vessel :2 at a rate of 0.26 gallon (2.17 lbs.) per minute. Under these conditions the composition of the setting bath was maintained at 58% .of N;N-'- dimethylacetamide and 42% of water throughout :the spinning, which consumed eight hours.

- The apparatus and method illustrated are'particularly advantageousin the" production of acrylonitrile polymer yarns whichare unique in that, as disclosed in the pending application of Howard M. Hoxie and Helen G.S ommar, Serial No. 83,374, filed, March 25, 1949, the amount of residual solvent present in-the yarnsiscritical I for optimum stretch 'and-impr'ovement in the tenacity at anygiventemperature from 100 C. up to the temperature at which the yarn is damaged. The yarn leaving the setting" bath comprising the solvent and precipitant contains an amount of solvent' which appreciably greater than 1.5% by weight; and ordinarily, prolonged washing would be requiredto-"reduce the solvent to less than 1.5%; However, in practicing this invention, the conditions,such as the length and width of trough 6. the angle of inclination of the troughwith respect to ve'ssels 2 and 9, the rate of fiow of the washing liquid through the trough countercurrentlyto the'yarn advancing from thebath, and the -temperature of the washing liquid may be selected so that the yarn leaving the trough after the initial washing contains less than 1.5% of the-spir'ming'isolvent and additional washings are not 'neces'sary prior to stretching the yarns at temperatures above 100 C.

Since certain changes may be made in carrying out the invention without departing from its spirit and scope, it is intended that all matter contained in the foregoing description is to be interpreted as illustrative and not in a limiting sense. In the claims, the terms "solven and solution are intended to include true solvents and solutions as well as dispersing agents and dispersions or colloidal solutions or mixtures in which the fiberor film-forming material is substantially uniformly dispersed. The term fibers is intended to include filaments and yarns.

I claim:

1. A method of forming artificial and synthetic fibers and other shaped articles which comprises continuously extruding a solution oi the material to be shaped into a setting bath comprising a mixture of the solvent and a liquid precipitant for the material to be shaped, which precipitant is anextractive for the solvent, 0on

tinuously withdrawing the shaped article from the setting bath to the atmosphere, continuously washing the article as it advances from the setting bath, and above the level of the setting bath, with a confined stream of liquid flowing countercurrently to the direction of travel of the article "x joi the isolation-- of tha material to be -shaped;

11 so that ithe relative proportions of precipitant -r:and1-:so1vent in .;the setting:bath.v are: thereby .::.-:imaintainedsubstantially constant fromizthe beginning torthegend or :the extrusion. 2, A method J as in claim 1, wherein the article iis'istretched simultaneously with washing thereof. 1 :3'.-A:method asin :claim 1', :wherein thematerial .tobe shaped comprises an acrylonitrile poly- :erner eontaimnggiby-weighiz mime-polymer mole- 'mcule -atnleast 70%- of'acrylonitrile.

1: '4; A method as in claim -1-,- wherein the-matei rial tcvbe-shaped is a :blend of an acrylonitrile ,-poly mer containing by :weight in the:;:polymer :molecule,; at least"70% or vacr-ylonitrile with a i=eopolymer of from 10 to-'7.0% of acrylonitrile m -and from30 to 90% Qi'a:vinyl-substitutedheteroe cyclic tertiary amine.

5-. A method-fas in claim -1, -Whereini:the material to.- be; shaped is a-zblend of an acrylonitrile 1 polymercontainingiby-weight in the polymer molecule, atleast 70%-:of-acrylonitrile andacoipolymer of-irom 16 to 7.0% of acryloni-trileand -..:from 30 to 9.0% of avinylpyridine. l fi. :A-method as in'claim l wherein thefmatere -rial tobeshaped is acellulose zorganic acidester.

7i A-methodv-as in claim 1,: wherein-the mate- 1 rial to be:shaped is secondary cellulose acetate.

1; 8. Amethod-as in claim 1; wherein the material to be-shaped is .a synthetic-resin.

\ 9. -A method of forming synthetic fibers from a "fiber forming-composition comprising an acrylo- -ni'tri-le polymer containing, by weight in the polymu-molecule, at least 70% of'acrylonitrile, which :comprises =continuouslyextruding a solution of V :-the polymer in dimethylacetamide into a setting batheomprisinga. mixture of water and dimethwylacetamide in a selected proportion between 20 1 :and 70 by volume; eon-tinuouslyiwithdrawing the rfibers irom the bath to. the atmospherercontinua eously washingthe fibers advancing from thebath,

andabove the level of the bath, with a confined stream of: liquid consisting ofwater and at-most a minor proportion of dimethylacetamide-flowing countercurrently to the direction of travel of the fibers, collecting the liquid from the washing :step, and continuously:deliveringlliquidcollected from the-washing step to the setting bath in a icontrolled amount which isdependent onthe relative proportion of water to dimethylacetamide in the liquid from the washing step and on the amount of -dimethylacetamide introduced 'into the 'bath'by the solution of the polymer, so

that the relative proportions of-water and 'dimethiylacetamide in the setting bathzare thereby maintained substantiallyconstant from the beginning to the end of theextrusion.

10. A method as in claim 9, wherein the fibers advancing from the setting bath are vwashed with water having a; temperature between room tem- :perature and 100 0.

11. A method as in-claim 9, wherein the fibers are stretched simultaneously with washing thereof.

12. .A'method as in claim 9, wherein. thefibers advancing from the setting bath are washed at a 1 temperature between room temperature and 100 tertiary amine.

14; A method as in claim 9, wherein the materia1 to be shaped is a blend of. an acrylonitrile polymer containing, by'weight in the polymer moleculaat least 7.0% of acrylonitrile with a copolymer of from 10 to of-acrylonitrile-and i from 30 to of a vinylpyridine.

HOWARD- M. HOXLE.

M flNo-referencesloited.

Claims (1)

1. A METHOD OF FORMING ARTIFICIAL AND SYNTHETIC FIBERS AND OTHER SHAPED ARTICLES WHICH COMPRISES CONTINUOUSLY EXTRUDING A SOLUTION OF THE MATERIAL TO BE SHAPED INTO A SETTING BATH COMPRISING A MIXTURE OF THE SOLVENT AND A LIQUID PRECIPITANT FOR THE MATERIAL TO BE SHAPED, WHICH PRECIPITANT IS AN EXTRACTIVE FOR THE SOLVENT, COMTINUOUSLY WITHDRAWING THE SHAPED ARTICLE FROM THE SETTING BATH TO THE ATMOSPHERE, CONTINUOUSLY WASHING THE ARTICLE AS IT ADVANCES FROM THE SETTING BATH, AND ABOVE THE LEVEL OF THE SETTING BATH, WITH A CONFINED STREAM OF LIQUID FLOWING COUNTERCURRENTLY TO THE DIRECTION OF TRAVEL OF THE ARTICLE AND CONSISTING OF THE PRECIPITANT AND AT MOST A MINOR PROPORTION OF THE EXTRUSION SOLVENT, COLLECTING THE LIQUID FROM THE WASHING STEP, AND CONTINUOUSLY DELIVERING LIQUID COLLECTED FROM THE WASHING STEP TO THE SETTING BATH IN A CONTROLLED AMOUNT WHICH IS DEPENDENT ON THE RELATIVE PROPORTION OF PRECIPITANT TO SOLVENT IN THE LIQUID SOLVENT INTRODUCED INTO THE BATH BY EXTRUSION OF THE SOLUTION OF THE MATERIAL TO BE SHAPED, SO THAT THE RELATIVE PROPORTIONS OF PRECIPITANT AND SOLVENT IN THE SETTING BATH ARE THEREBY MAINTAINED SUBSTANTIALLY CONSTANT FROM THE BEGINNING TO THE END OF THE EXTRUSION.

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