US2510135A

US2510135A - Method for spinning artificial filaments

Info

Publication number: US2510135A
Application number: US770372A
Authority: US
Inventors: Pedlow John Watson; Wesley L Webb; Ingham S Roberts
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1947-08-25
Filing date: 1947-08-25
Publication date: 1950-06-06
Anticipated expiration: 1967-06-06
Also published as: BE484348A; NL74039C; GB664829A; FR970673A

Description

June 6, 1950 a. w. PEDLOW ETAL 2,510,135

' METHOD FOR SPINNING ARTIFICIAL FILAMENTS Filed Aug. 2511947 JNVENTOR. JOHN WATSON PEDLOW WESLEY L. WEBB INGHAM 6. ROBRT5 i atenteci June 6, 1950 UN lT-ED STATES PATENT OFFICE METHOD FOR SPINNING ARTIFICIAL 1 FILAMENTS Delaware ApplicationAllgust 25, 1947, Serial No. 770,372

20 Claims.

vl 'iihisinvention relates .to methods of spinning artificial filaments by the wet-spinning system in accordance with which filaments extruded through orifices of a spinneret enter a coagulating liquid" whichserves to set up the filaments either by removal of solvent or by chemical reaction therewith.

In the past, there have been many attempts to controlthe flow of the coagulating liquid relative to the filaments issuing from the spinneret in order. to. produce artificial filamentshaving better qualities, and particularly uniformity of strength, extensibility, nd dyeing throughout the length of eachfilamentrand also, among the several filamerits issuing not only from a single spinneret but from allof the spinnerets in a given machine. However, the spinning procedures heretofore employed allow the filaments to be subjected to variable stresses by the coagulating liquid before theifilaments were toughened by sufiicient setting or'coag'ulation to be insensitive to such variable influences so that the final physical properties of the filaments were non-uniform, and this nonuniformity existed along the length of each individual filament as well as between the several filaments issuing from the same or diiierent spinnerets. In general, therefore, such attempts have only been partially successful.

it has now been discovered that it is'po'ssible to produce in a practical manner artificial .filaments which are markedly improved in respect to strengths, both wet and dry, extensibilities, wet and .dry, and dyeing, particularly in respect to the uniformity of such characteristics among the several filaments issuing from a single spinneret as well as along the length of each filament and even among the filaments issuing from several spinnerets, by an'improved manner of controlling the action of the coagulating liquid upon the freshly extruded filaments.

In generaLthe new process involves forcing a small'stream orjet of the coagulating liquid to move midairalong'with the-freshly extruded filamentbundle through a straight path at substanvtially the same speed as thefilaments while avoiding irregular disturbances resulting from part of the liquid running back upon or ahead of, or dripping; off,-.the traveling" filament-liquid stream until. such stream-reaches a predetermined stage at. which removal of the liquid can be accomplished in a uniform manner and under conditions subject to control.

It has been found that a smallbutsubstantial quantityof liquid will adhere as abody td'the filaments so thatsubstantiallyallof such liquid will travel with the filaments and at the same velocity as the filaments over considerable distances through the air without any noticeable change of velocity regardless of the direction of the night through theair. The amount of liquid that 11 thus adhere to the filament bundle and be sustained and moved along bodily with it, in spite of gravitational and air friction forces depends on a number of factors including the particular filament-forming material, the number of filaments making up the bundle, and the nature of the ceagula-ting liquid, particularly its surface tension'viscosity and tendency to adhere to the material constituting the filaments. The maximum amount that can thus travel with the filaments is not inconsiderable, however, and it has been found that, in generahmuch less than the maximum permissible amount will in a relatively short passage even at spinning speeds higher than conventional, set up the filament-forming streams of material to asufiiciently firm condition that the filaments leaving this stage' of-production can stand up under all the customary subsequent treating stages without being unduly sensitive to irregularities therein.

in order to limit theamount of liquid traveling with the thread, the spinneret' may be disposed withina chamber to whichthecoagulating liquid is supplied, which chamber is provided with an opening in front of the'spinneret face through which the filaments accompanied by the liquid are withdrawn. This opening may be of surficiently small diameter to limit the amount of liquid passing out ofthe' chamber with the filaments; depending upon the nature ofthe materiai forming the opening and the precise contour at the opening, the diameter of the'stream issuinginay increaseor-decrease somewhat from the diameterof the opening and accordingly the selection'of the size of the opening should take thisinto account. The chamberabout the spinneret should be kept filled with the coagulating liquid which involves the feeding of suchliquid thereto at a rate'sufiicientto equal the rate of withdrawal bythe filaments. In the vicinity of the opening, the contour of wallsabout the passage or zonewithinthe chamber is preferably streamlined to assure viscous flow of the liquid as it approaches the opening immediately before passage therethrough. This can be adequately met by gradually tapering the inside wall or walls of the chamber toward the opening.

The accompanying drawing is illustrative of the spinning processes of the present invention.

Figure 1 is an axial-section-through a spinneret assembly which may be used in performing the invention,

Figure 2 is an elevation showing one spinning system,

Figure 3 illustrates a modification,

Figure l is a plan view of the embodiment of Figure 3, and

Figure 5 is illustrative of a modification in which spinning is performed in a downward direction.

As illustrated in Figure 1, each spinneret is advantageously disposed within an individual chamber to which the coagulating liquid is supplied, though it is to be understood several spinnerets may be disposed in a common chamber. In Figure l, the spinneret 3 is held in place 1113011 a pply pipe 4 by means of the coupling 5, a gasket 6 being present to provide a seal. A housing member '3 is held in place upon the coupling member 5 by means of the sleeve 8 which threadedly engages the outer periphery of coupling 5. The member 7 contains the chamber 9 and has a. recess I9 within which a guiding element I! having an orifice IIb fits. A gasket I2 is seated between the member I I and the shoulder at the back of the recess Ii] and the orificed member I I is held in place by a coupling sleeve 53 which threadedly engages the outer periphery of the housing member I.

The coagulating liquid is supplied to the charm her i by means of the conduit it which may be the discharge conduit of a metering pump 55 such as a gear pump. The conduit I4 fits into the housing member I and is arranged to direct the coagulating liquid around the body of the spinneret 3.

As shown. it is preferable, when spinning certain materials into certain baths which develop gases during the spinning such as viscose into an acid regenerating bath, to have a portion or even all of the coagulating liquid stream discharged by the conduit I 4 directed across the face 3a of the spinneret in order to prevent accumulation of bubbles on the spinneret face. The arrows generally indicate the flow of the coagula ing liquid around the spinneret and then into the region immediately front of the spinneret face. The inner end wall of the member II projects inwardly of the adjacent inside wall of the housing and this projecting ledge or shoulder assures that the liquid flows from all sides of the outer periphery of the spinneret toward the center of its face. As the liquid. flows inwardly along the face. it contacts with the filaments leaving the several orifices Within the spinneret, sweeps gas bubbles from the face, and joins with the filaments in the main current of flow axially of the spinneret and of the tapered bore I In. in the guiding member I i. The transverse flow of the coagulating liquid over the face of the spinneret, though shown as proceeding from all points of the spinneret face periphery, may proceed from one side only of such face so that the transverse flow may deflect the filament-forming streams toward the other side of the spinneret face, as is shown in the copending patent application of Roberts Serial No. 698,437, filed September 21, 1946. This sweeping of the spinneret face is unnecessary, however. when spinning other materials or under conditions which do not develop gas bubbles.

The size of the opening I ll) may be preselected, as more particularly described hereinafter, to limit the diameter of the stream or jet of liquid traveling with the filaments from the spinneret assembly. The guide element or nozzle II is preferably made of material which is not only resistant to corrosion, erosion, and abrasion, but exerts but little abrading action on any filaments that may occasionally rub thereagainst during the initial lacing or threading operations. Glass, porcelain, agate, lava, and artificial materials of the latter type, such as that available under the trade name Alsimag may be used to advantage for this fitting, The tapered passage I la merging into the opening I Ib may have any length up to 10 cm. or so but is preferably relatively short so that the distance from the opening I II) back to the spinneret face is not over 2 or 3 cm.

As illustrated in Figures 2 to 5, the spinneret assembly may be arranged to discharge the liquid carrying the filament bundle in any direction from vertically downward to vertically upward. Regardless of the direction taken by the filaments during spinning, i. e., downwardly or upwardly or at an inclination to either direction, the control of the coagulating liquid supplied to the chamber may be accomplished either by means of a metering pump such as a gear pump or by the maintenance of a predetermined pressure upon the liquid supplied to the chamber. When dependence is placed upon a predetermined pressure rather than upon a metering pump, it then becomes more important to predetermine the diameter of the opening III) in order to limit the amount of liquid issuing with the filament bundle. Regardless of which system is employed for controlling the supply of coagulating liquid to the chamber, it is of paramount importance to keep the chamber full of coagulating liquid at all times during spinning and also to provide a gradual taper along the bore I Ia approaching the opening Iib. This taper assures substantially viscous flow of the coagulating medium through the guiding member I I and into the free flight or course through the air. Some turbulence may be present in the vicinity around the face of the spinneret where the coagulating liquid sweeps transversely of the filaments and then must change direction to flow through the member II, but is preferably minimized by forming the parts, such as the member II and the spinneret body, with smoothly rounded contours. Whatever small amount of turbulence there may be at any part of the passage followed by the coagulating liquid through the chamber, the fact that the liquid is continuously supplied at a constant rate assures substantially uniform treatment of the filaments within such chamber.

The present invention, however, is more vitally concerned with what occurs after the filamentcontaining coagulating liquid stream or jet leaves the spinneret assembly up to the time of the removal of the excess liquid from the filament bundle. If the liquid carried by the filament bundle begins to flow back down the bundle in the case of upward spinning, irregularities immediately occur which influence the properties of the filaments. Thus, as the liquid starts to flow back down the liquid-carrying filament stream, it disturbs the upward traveling body of liquid and in a fashion characteristic of liquid, 2. more or less irregular wave pattern is generally set up by such disturbance. The result of such a disturbance is inherently the production of an irregular filament. Such irregularity in the filament may not always be detectable in terms of its diameter but it does show up in variations of strength, extensibility and dye receptivity along the filament. Similarly, in downward spinning, the overtaking mass-of liquid-similarly setsup a disturbance having a-wavea pattern. of irregular character :whichagaininfiuences the filaments irregularly. --Whenthe'di-rection of spinning is horizontal, upward ror downward-at anhinclinationf to the vertical, part or the liquid maydrip off the course of the filaments at irregularly varyingdistancesfmm the spinneret assembly.

All i of these irregular occurrences .are avoided in accordance with the present invention by limiting the amount of liquid in" the jet accompanying the filament. bundle-to the amount which is able to cohere as a unit and toadhere' bodily to the given filament bundle throughoi-it the free fiight in midair in the particular direction. at which spinning occurs Without the-.back.. fiow, overtaking,,ord ripping so that the liquid at any point along the bundle asit travels from the spinneret. assembly .has substantially the same linear velocity throughout itsicross section as' the filaments .traveling .therein. It is a relatively simple matter to determine'when-all of the liquid travels at the same speedas the filamentssince, when this condition is, present, i the. diameter of the stream remains constant from apoint near the exit opening of the spinn'er'etassembly all the way. to the surface whichremoves the liquid from" the filaments. The amount of liquid that can'be carriedin this fashion depends. upon the particular nature of the spinning. material and the coagulating liquid, but in general,. it has been determined that a safe upper limit of load is 01001 gram per centimeter per filament for bundles containingup to about 300 filamentsand optimum results are obtained. if the load per filament is not over 0.0006. gram per centimeter. The latter limitis applicable to bundles having any number of filaments such as .1200. 'In the spinning of viscose in a dilute acid aqueous coagulating bath having a specific gravity of l;3 to 1L4, it has been found that the limit of load is reached when the filament-containing liquid stream has a diameter of3 mm. and optimum results are obtained if the diameter does not exceed '2 mm.

The amount of liquid in the jet containing the I filaments may be controlled in various ways. The size of the opening I lb can. be predetermined to limit the diameter of the liquid jet issuing and the velocity of the jet can'be controlled by preselecting the pressure exerted upon the liquid in the chamberil, or by the operattion of the metering pump, depending upon which device'is employed. When operated in thisfashion, the size of opening may vary in a'practical'fashion'be-V tween about 0.5 mm.-to "3.0 "mm. in diameter though lesser diameters not exceeding 2 mm. are preferred.

When spinning upwardly, some reliance may be placed upon the natural tendency of the filament bundle to carry the liquid with it out of thelxopening, in which eventthe diameter oflthe opening can be much larger-than and even several. times the above-mentioned 3 mm. limitgbut this? is satisfactory only when the distance from,

the'lface of the spinneret to the liquid level in' the exit opening in the chamber is not-over 3pm. andfis preferably -2 cm. or less. The filamentcontainingjet of liquid issuing in this case Jacquires its velocity from the filaments-being withdrawn from the assembly. The filament bundle itself, .in this'casecan be used 'tocontrol the diameter; of the liquid stream, and this" canbe effectively done by -varying'ithe spacing bet-ween the'orifices of the spinneret. -Whcn wi'de'spacing such asv 0-.020 toaozo ic inch between centers of adjacent. orifices'in a row and between centersof -adjacentrows,- is used,- a relatively larger diameter of liquid stream will move away-With the filaments, whereas a closer-spacing, suchas 0.005'to 0.015 inch between centers of adjacent orifices in -arow and between centers of adjacent rows, provides a smaller diameter; and as indicated-above, the smaller diameter streams are preferred. Thecloser spacing becomes more advantageous as the number i of filaments in the bundle-becomes larger.

lniaccordance with the present -invention, it is. desirable to remove the liquid in --a controlled manner. and-this is preferably done -by-:contacting the filament-containingstream with a -surface having a linear speed substantially thesame as that ofthe'filaments. Such surfacemay be inclined to one side ofthe runningfilaments-so thatthe liquid runs down the surface may from the filaments'as they bear against the surface. Or the'surface.mayloe. a porous one so that the liquid fiows to the interior thereof. -A-lternatively a rotarydrumhaving a linearperipheral speed the same as thatof the filaments may .be lightly pressed against the straighhcourse of the filaments before they. reach the thread-advancing device, such'as. l6 inEigure 2, and the liquid removed by the surface may be wiped off the drum at a: point away from that in contact with the filaments. vAgain, the surface may rotate .at a

sufficiently high speed (though still the same linear speed as that of the filaments) to throw the liquid ofithe filament bundle by centrifugal force as the filament, bundle travels aroundsuch surface.

Figure 2 is illustrative of the pr esent.invention in which spinning is performed in avertical and upward direction. As shown, the filaments extruded through .the orifices of spinneret 3 within the chamber in housingl which issupplied with coagulating liquid by the conduit.- leave the opening I i b. in a streamof liquid travel-- ing therewith at substantiallythe same speed. The filaments pass directly along a straight, path from the opening 4 lb to a thread-advancing device such as the godet it having an inclined axis and about which the filaments are lapped by means of a roller guide ll. The godet I6 is driven at any 'desiredspinning speed from meters upwardly and in accordance with the present invention it has been found that spinning speeds as high as 200 meters per minute can be employed with satisfactory production of filaments. When the filaments first reach the peripheral surface of godet [5, they are pressed thereagainst and the liquid travels down to the rim I8 of the tgodet from which it may fiow into a gutter l9 'therebelow. Since all of the liquid carried with the fila-rnents travels at the same speed throughout the passage from the spinneret to the godet l'6, and the godet I6 removes the liquid uniforr'nly from each point of the filament bundle as such points reach the surface in succession, thereis- 'no opportunity for the fiow of liquid back down the filaments and the irregular disturbances developed thereby.

Fromthe godet [6, the bundle of filaments from which'the liquid has been removed, may pass to a second thread-advancing device which may comprise a godet 20 and associated wrap-displacingag-uide roller 2 l. Between the'zgodets l tz'and 20, :the filaments may bestretchedfor: allowed to relax in a fashion which is conventional in the art. From -the:.- godet:2'0, the filaments may' proceed to additional thread-advancing devices to receive additional stretch Or to allow shrinkage after one or two stages of stretching, or the filaments may proceed to other thread-advancing devices upon which they may be treated with liquids, such as for washing, bleaching, desulfurizing, decoppering, and the like. Whether or not the filaments leaving the godet 2!! pass over additional thread-advancing devices for after-treatment, further stretching and the like, the filaments are ultimately collected either in the form of an untwisted or twisted package. For example, they may be collected in a centrifugal pot in the fashion conventional in the viscose spinning process; or they may be collected by winding on a bobbin without twisting; or they may be collected on twisters of the cap, fiyer, or ring type.

The process of the present invention is particularly adaptable to continuous spinning processes and especially to such processes as require high speed spinning, such as that disclosed in the application of Stanley and Lowe, Serial No. 504,664, filed October 2, 1943. In this latter type of process, the filament proceeding from the spinning stage of the continuous spinning machine passes to one or more thread-advancing devices which rotate at sufficient speed to throw the liquid off by centrifugal force and a jacket is provided about the thread-advancing reel with its inner surface closely spaced about the bars of the reel so as to deflect the liquid thrown out to the surface back to the helix of filaments carried by the reel.

Figures 3 and 4 show a modification in which the filaments leaving the opening Hb in the housing around the spinneret 3 pass upwardly at an inclination to the vertical and in this embod ment. the filaments in the jet of the coagulating liquid proceed directly to a thread-advancing reel 22 rotating at sufiiciently high speed to throw the liquid from the helix of thread carried thereon. As shown more particularly in Figure 4 a guard member 23 is provided around the zone of the reel to which the filaments are first led. This guard member receives the liquid thrown ofi by centri ugal force and discharges it through a drain 24 connected to the bottom thereof. Beyond this zone of the reel, a jacket 25 is disposed entirely surrounding the reel and having an ins de deflecting surface 25. Annular grooves 2'! and 28 are di posed at each side of the sur ace 26 and communicate with drain pipes 23. Add t onal coagulating li uid may be supplied to this jacket by means of the pipe 38 communining course between the spinneret assembly and the first thread-advancing device before subsequent washing, desulfurizing, etc., can be performed on a continuous spinning machine.

The coagulating liquid supplied to the jacket 25 is repeatedly thrown OK the helix of filaments and deflected back thereon to provide a thorough washing in the manner disclosed in the above mentioned Stanley and Lowe application. From this reel, the filaments may proceed to a second reel operating at higher peripheral speed to effect stretching. A liquid may be applied to the filaments as they pass between the reels to facilitate stretching, such as hot water in the case of viscose. Then the filaments may proceed either to a collecting device or over a plurality of liquidtreating reels before being collected.

Figure 5 illustrates the directing of the filaments downwardly in a substantially vertical direction from the opening I lb of the housing I about the spinneret 3. The coagulating liquid supplied to the chamber within the housing I by the conduit [4 is metered by the opening Ilb so that a limited weight of liquid travels with the filaments to the thread-advancing device 32. In this embodiment, the distance between the opening [lb and the point of first contact with the thread-advancing device 32 is preferably sufficient to provide substantially complete setting up of the filaments so that when they make contact with the device 32, they are no longer deleteriously aifected by any accumulations of liquid on the device 32 with which they may make con-- tact. However, the distance between the spinnere't assembly and the device 32 may be less than that just specified, in which event it is desirable to incline the device 32 in the manner of device l8 in Figure 2, or to operate it at high peripheral speed as in Figure 3, in order to throw the liquid oil? by centrifugal force.

While the invention is applicable to the spinning of filaments of any material by the wet spinping procedure, the following examples illustrate the invention with reference to the spinning of viscose. These examples make use of a viscose containing l /2% cellulose and 6%% sodium hydroxide spun at a common salt point of 4, into a coagulating bath containing 9 to 10.5% sulfuric acid, 3% zinc, and 20 to 22% sodium sulfate at a temperature averaging C. and having a specific gravity averaging about 1.38. The tabulated examples indicate the conditions which provide the travel of the coagulating liquid with the filaments at the same speed without back eating with the bore 3 I into the surface 26. This 55 flow, dripping or overtaking.

No. of in. of 'lotal Die. of Smnn. Rate of Bath Vi t. Ex. Ffla- Tmmd Denier ments 11b Speed Bath Feed Ffl. let on Yarn Mm. MJmin. ccjmin. Mm. g./r'm.

is particularly desirable in the case of spinning a viscose solution which generally takes additional contact with the coagulating liquid beyond that which could be effected in a single run- The present invention not only controls the flow of coagulating liquid so that the amount carried by the filaments is not so excessive as to develop back fiow and dripping and like irregular '9 disturbances but. it also economizes on. the amount of coagulating liquid neededffor complete s et' uph Furthermore, it assures that the coagulati'ng liquid which makes contact with the filaments immediately after the material leaves the spinneret orifices has a definite composition which is constant throughout the period of'spinning. ThUS EaChQDOI'tiOI'l. of the length of each filament is in contact. with a coagulating bath havingadefinite constitutionat any point of its passage between the. spinneret orifice and. the stage at which coagulating liquid is removed' Fresh coagulating liquid of the predetermined constitution makes the first contact withthe filaments issuing "from the spinneret andisuch' liquid, contam nated. as. a result. of contact with the. filaments, is notallowed to tarry atthe. spin-.- neret face to react with. subsequently issuing filaments but instead is continuously withdrawnwith the filaments so-thati fresh liquid replaces thatjat the spinneret face, in-a continuous fashion. action is assured iby. the provision of. theirelatively smallchamber about the spinneret which. is kept filled with coagu atingliquid. and is rapidly withdrawn with the filaments. Since the coagula'ting liquid always has avelocity in the. direction of flow of theefilaments from the spinneret face, there is verydittle. of .what may be termed a, bath. drag exerting any substantial tension uponthe. filaments as they pass from the spinneret to the stage-at which the coa ulating liquid i removed. In addition, the d rectitravel of the filaments-from the spinneret .face to the sta eat which theliquid-is removed in. a controlledand' uniform fashion assures t at the characteri ticsof: the filamentsrare as uniform as possible. The pre ent invention is particularly, ad-

vantageous in-high speed spinning andi'onthis:

purpose, its preferred form makes use of control-- led'pressureora metering pump for delivering thecoagulatingliquidtothe chamberabout theispin'. neret at a: predetermined "rate; in. combination with the presele'ctionr of" the diameter: of the opening .in: the ch amber through which: the; fila,

ments'are discharged forcontrollingithe diameter. of the stream issuedtherefrom so thatlin effect,-

the: liquid discharged vfromiithat opening. serves toacarry the fi aments rather than-the converse; Whentoperatin in this fashion, a h h speed aiet "'ssues and'rassists the withdrawing deand are coagulated to filaments in the coagulat ingliquid stream, imparting a. predetermined constant velocity to the filaments as they proceed in said straight path, forming the coagulating liquid stream at a point within a distance of about centimeters in front of the spinneret into a jet having substantially the same velocity as the filaments and flowing in free flight through the air along the straight path of the filaments, controlling the amount of liquid in the jet to assure that all of the liquid adheres to and travels substantially at the same velocity as the l0 filaments throughout saidstraightpath, afidtfiefi continuously removing, liquid from the filaments in a, uniformly controlled manner at a predetermined p'oi'ntof tllestlai'ght path.

2: Tlifmethbd of claim Tin which the di're' tion of extrusion is; upward: I

3: T e method of'claim 1111 which the direc tion'bf'extrusion' is downward;

4. The'method" of claim 1' in"which" the di rect on 'of "extrusion is vertically upward.

5'; The -rrietli'od"of claim 'r'in which the directi'on' of'extru'si'on is vertically downward.

6. The method'o'ffproducing artificial filaments comprising continuously extruding a filamentfcirniingmate'rial through the orifices of a spinneret me a stream offcoagulating 'liquidflowirlg argraduauy increasing velocity in the generaldi re'ctionof extrusion; directing, the filament-formingstreams of material ina straight path as they proceed 'from. the spinneret and are coagulated to "filaments inv the coagulating liquids tream; imparting. apredetermined constant velocity to the filaments along said straight path; forming the coagulating l quid stream. at a point within a distance of about 10 centimeters in front of the spi'n'neret! into a let havingsubstantially the same velocity as the filaments, flowing-fin free flight through the air alongthe straight path of the filaments, and having a weight per cen-- timeter of. length not over 0.001. gram per filamentso as to assure that. all of. the liquid-adheres. to and travels "substant ally at the same velocity, as the file ments. throughout saidstraight path, and then continuously removing liquid from the filaments in auniformly control ed manner.v atapredetermined point of the strai ht path.

If The methodof claim 6'in Whichthe jet has a diameter not over 3mm. v

s. The method of 'claim s in which the let hasa-diameter notover 2 mm.

9. method of claim 6 in whichthe jet-has. a. weight per centimeterof length not over.0.0006' gramper filament and a diameternot over 3 mmr 10. The method oiiclaim Sinwhichthe jet has.

aweight per centimeter of length not over'0l0006:

gram per. filament and a diameter not over: 2 1pm.. 7

11. The methodwof producingartificial fila-- ments comprising continuously extrndingra filament-forming material through the-orifices of a; spinneret into a streamof coagulating liquid;- moving r the liquid: in said stream away. frorni'zth'e spinneret at gradually increasing -rvelocity in-the general direction of extrusion. withdrawing the: fil-ament-iorming'i streams of: materialafrom the spinne-ret in a straight pathat a predetermined constant velocity, forming-the coagulating: liquid streamuat a point with-iniaidistance: of about 10 centimeters.in' fro'nt of the spinneret intora-- ;iethaving substantially the same velocityas the ma ments. and flowing in free'sfiight. through the air" alongrthe straight" path of the filaments; conwtheamount of liqui'dvin the-jet toassu-re- 1 ofcthe. liquidfsadh eres" to and tra vels" sub stantially at the same velocity as the filaments throughout said str a eht pathg and then con tinuously l emovinIg llquid frornthe nl'aments nra to form a jet of the liquid issuing from the opena ing, continuously withdrawing the filaments through the opening and directing them with the jet in a straight free flight at substantially the same speed as the jet, controlling the amount of liquid in the jet to assure that all of the liquid adheres to and travels substantially at the same velocity as the filaments throughout the free flight, and then continuously removing liquid from the filaments at the end of the free flight.

15. The method of claim 14 in which the jet has a Weight per centimeter of length not over 0.001 gram per filament and a diameter not over 3 mm.

16. The method of claim 14 in which the jet has a weight per centimeter of length not over 0.0006 gram per filament and a diameter not over 2 mm.

17. The method of producing artificial fila-, ments comprising continuously extruding a filament-forming material through the orifices of a spinneret into a confined passage having a restricted exit opening not over about 10 centimeters from the spinneret face and a transverse crosssection along a portion thereof decreasing gradually to, and merging with, the opening, continuously directing coagulating liquid of predetermined constitution through the passage and the opening at sufiicient velocity to form a jet of the liquid issuing from the opening, continuously withdrawing the filaments through the opening and directing them with the jet in a straight free flight at substantially the same speed as the jet, controlling the amount of liquid in the jet to assure that all of the liquid adheres to and travels substantially at the same velocity as the filaments throughout the free flight, and,

then continuously removing liquid from the filaments at the end of the free flight.

18. The method of producing artificial fila ments comprising continuously extruding a viscose spinning solution through the orifices of a; spinneret into a confined passage having a restricted exit opening not over about 10 cen-" timeters from the spinneret face and a transverse cross-section along a portion thereof, decreasing gradually to, and merging with, the opening, continuously directing an aqueous, acid coagulating liquid transversely past the viscose streams at the position of extrusion and then through the passage and the opening at sum-' cient velocity to form a jet of the liquid issuing the same velocity as the filaments throughout the free flight, and then continuously removing liquid from the filaments at the end of the free flight.

19. The method of producing artificial filaments comprising continuously extruding a viscose spinning solution through the orifices of a spinneret, continuously'directing an aqueous, acid coagulating liquid transversely past the viscous streams at the position of extrusion into a zone surrounding the viscose streams, directing the filaments from the vicinity of the spinneret along a straight path comprising beyond a distance not over about 10 centimeters from the spinneret face, a free flight portion proceeding at a predetermined constant velocity, passing all of the coagulating liquid contaminated by proximity to and contact with the viscose streams with gradually increasing velocity through said zone away from the spinneret in the same direction as the viscose streams while supporting the filaments thereby until the velocity of the liquid is approximately the same as that of the filaments, controlling the amount of liquid in contact with the filaments along the free flight portion to assure 20. The method of producing artificial fi1aments comprising continuously extruding a filament-formin material through the orifices of a spinneret into a stream of coagulating liquid flowing in the general direction of extrusion, directing the filament-forming streams of material in a straight path as they proceed from the spinneret and are coagulated to filaments in the coagulating liquid stream, imparting a predetermined constant velocity to the filaments as they proceed in said straight path, forming the coagulating liquid stream at a point within a distance of 3 centimeters in front of thespinneret into a jet having substantially the same velocity as the filaments and flowing in free flight through the air along the straight path of the filaments, controlling the amount of liquid in the jet to assure that all of the liquid adheres to and travels substantially at the same velocity as the filaments throughout said straight path, and then continuously removing liquid from the filaments in a uniformly controlled manner at a predetermined point of the straight path.

JOHN WATSON PEDLOW.

WESLEY L. WEBB.

INGHAM S. ROBERTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,493,545 Holken, Jr May 13, 1924 FOREIGN PATENTS Number Country Date 394,049 Great Britain June 22, 1933

Claims

1. THE METHOD OF PRODUCING ARTIFICIAL FILAMENTS COMPRISING CONTINUOUSLY EXTRUDING A FILAMENTFORMING MATERIAL THROUGH THE ORIFICES OF A SPINNERET INTO A STREAM OF COAGULATING LIQUID FLOWING IN THE GENERAL DIRECTION OF EXTRUSION, DIRECTING THE FILAMENT-FORMING STEAMS OF MATERIAL IN A STRAIGHT PATH AS THEY PROCEED FROM THE SPINNERET AND ARE COAGULATED TO FILAMENTS IN THE COAGULATING LIQUID STREAM, IMPARTING A PREDETERMINED CONSTANT VELOCITY TO THE FLAMENTS AS THEY PROCEED IN SAID STRAIGHT PATH, FORMING THE COAGULATING LIQUID STREAM AT A POINT WITHIN A DISTANCE OF ABOUT 10 CENTIMETERS IN FRONT OF THE SPINNERET INTO A JET HAVING SUBSTANTIALLY THE SAME VELOCITY AS THE FILAMENTS AND FLOWING IN FREE FLIGHT THROUGH THE AIR ALONG THE STRAIGHT PATH OF THE FILAMENTS, CONTROLLING THE AMOUNT OF LIQUID IN THE JET TO ASSURE THAT ALL OF THE LIQUID ADHERES TO AND TRAVELS SUBSTANTIALLY AT THE SAME VELOCITY AS THE FILAMENTS THROUGHOUT SAID STRAIGHT PATH, AND THEN CONTINUOUSLY REMOVING LIQUID FROM THE FILAMENTS IN A UNIFORMLY CONTROLLED MANNER AT A PREDETERMINED POINT OF THE STRAIGHT PATH.