US2788256A - Method of spinning filamentary strands - Google Patents

Description

April 9, 1957 G. M. ALLEN METHOD OF SPINNING FILAMENTARY STRANDS Filed June 2, 1952 INVENTOR.

" GEORGE M. ALLEN AT) Er United States Patent METHOD OF SPINNING FILAMENTARY STRANDS George M. Allen, Swarthmore, Pa., assiguor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application June 2, 1952, Serial No. 291,185

1 Claim. (Cl. 18-54) This invention relates to method of spinning strands of filamentary material in the presence of liquid materials applied thereto to harden or set the filament-forming substance. The method is particularly applicable to the spinning of viscose rayon yarns, and for purposes of illustration, the invention is described with respect thereto.

In conventional spinning processes involving the step of spinning a filament-forming material into a bath of liquid coagulant, spinning is ordinarily conducted in such amanner as to cause contamination of the spinning bath by the products of reaction and the dilution of the bath by Water, formed also as a product in the reaction of the coagulant with the filament-forming material. Such contamination or the dilution of the spinning bath necessitates the recirculation in large quantities of the bath liquid and the introduction of large amounts of concentrated coagulant solution to maintain the concentration of the bath at a level satisfactory for proper coagulation. Moreover, the products of reaction which contaminate the bath reduce the efliciency of the coagulation treatment.

It isan object of the invention, therefore, to provide, spinning method whereby a liquid coagulating material is brought into contact with a strand-forming material immediately after extrusion and is prevented from re turning to the supply source to avoid dilution and contamiriation thereof, and to eflect a more efficient use of the coagulant itself. It is another object to provide a method for wet-spinning a multifilament strand by which the material of the strand may be subjected, in rapid sequence, to an initial coagulation treatment and a sub sequent regenerating treatment prior to a stretching treatment. Still another object is to provide a method for preventing contamination and dilution of a spinningba'th while applying various treatments to the filament -forming material, regardless of whether the filament-forming material is extruded into a stationary bath of coagulent' or into a tube conducting a concurrent stream of liquid coagulant. A further object is to provide a method in which a godet is employed for abstracting liquid from a liquid-laden strand passing upwardly onto the godet, and discharging the liquid from a po'intspaced further along the periphery of the godet to prevent run-back along the section of strand approaching the godet. Still another object is to provide a method in which a snubbing systemcomprising godets is utilized for handling. a section of strand which is passing through the early stages of conversion from a filament-forming material into filaments of substantial tensile strength. Other objects, features and advantages will become obvious from the following description of the invention and the drawing relating thereto in which Fig. l is a diagrammatic view of apparatus for processing a liquid filament-forming material into strand packages, with portions ofthe structure shown in section; Fig. 2 illustrates a godet system used in the apparatus of Fig. l with portions of the structure shown in section;

Patented Apr. 9, 1957 Fig. 3 is a diagrammatic view of a modified construction of a portion of the apparatus illustrated in Fig. 1;

Fig. 4 illustrates, partly in section, a portion of the apparatus shownin Fig. 3;

Fig. 5 is a vertical section taken approximately along a plane normal to the axis of a godet, such as used in the apparatus of Fig. 1;

Fig. 6 illustrates a modified apparatus for handling a running strand;

' Fig. 7 illustrates another modified apparatus for handling a running strand; and

Fig. 8 is a modification of a portion of the apparatus illustrated in Figs. 1 and 3.

in brief, the present invention relates to a method of passing a freshly-spun liquid-laden strand through a godet system which comprises one or more godets, and discharging the strand, with the filamentary material thereof in a substantially converted or regenerated condition, toward a takeup means operating at a linear speed greater than the peripheral speed of the godets. The

godets preferably comprise annular transversely-toothed surfaces or serrated portions and smooth surfaces so that the strand, after being exposed to a liquidcoagulant, may be first supported on the broken surface of a toothed section with very little tension and while in a relatively plastic state, and then on the smooth section. The smooth sections are more satisfactory for snubbing the strand since tension may be applied by the take-up means without damaging the strand, and for other reasons explained hereinafter. When the strand passes in an upward direction from a liquid coagulant, the liquid carried by the strand is rapidly separated therefrom by godet having teeth, the forward surfaces of which are canted forwardly in the direction of rotation. The axis of one godet is preferably canted with respect to the axis of the other so that the strand may be advanced lengthwise thereof.

in one method of the invention, the lower godet is canted downwardly so that the smooth portion thereof may be run partly immersed in a bath of liquid, heated sufficiently to accelerate the regeneration of the cellulosic material comprising the strand. The application of a heated regenerating liquid may be suppiemented by addi, tional duct means mounted for discharging the liquid onto the smooth sections of the godets, or by means for conducting some of the liquid lengthwise of a portion or" the path of the strand as it passes from the godets to the take-up means.

Fig. l is a diagrammatic illustration of apparatus for spinning a yarn of artificial filaments in accordance with one method of the invention. A spinneret is supported in a tank 6 having overflow means, such as tube 7, for maintaining a liquid coagulant at a predetermined level 8. A filament-forming material is extruded from the spinneret into the bath in the form of fine streams that are con verted by the coagulant into filaments comprising the strand 9. The strand passes upwardly onto the serrated portion or toothed-surface of a godet it) having teeth 11 which are canted forwardly in the direction of its rotation as shown in 2. One or more windings of the strand 9 are supported around the godet 1G and anether godet 12, having one port-ion of its peripheral surface smooth and another portion fluted. The godets are connected in drive relationship by an arrangement, such as the sprocket and chain system 13 shown, whereby they may be driven by a 3 formed betweentheteeth. Conversely stated, the leading surfaces of the teeth or flutes 11 extend radially inwardly froui the outer diameter of the fluted section of godet and backwardly with respect to the direction of rotation of the godet.

The godet 12 may be provided with teeth or serrated portion similar to those of godet lit Advancement of the thread in a direction lengthwise of the godets may be accomplished by guides, or the godets may be supported as shown with their axes canted with respect to each other. One important function of the godets 1t and 12 is to separate a liquid carried from the tank 6 by the strand, so that it may be collected in a hood 14, which surrounds the godets, and is thereby prevented from returning to the tank 6. As the process and apparatus being described is highly adaptable to the making of large denier yarns such as used in tire construct-ion, the yarns, immediately after formation near the spinneret face, are relatively thick, plastic and incompletely coagulated, and are capable of carrying substantial quantities of liquid from the tank 6 upwardly toward the godet It. Apertures are provided for the yarn through the hood 14, one (13a) along the path of the yarn as it passes from the bath to the godet '10, and the other (1311) along that portion of path extending from the godet 10 toward a trough 15. To prevent a return to the tank 6 of the liquid carried from the bath by the strand 9, forwardly canted teeth are required, particularly on the godet which first engages the strand. Such teeth abstract and lead the liquid from the strand into the pockets formed between the teeth, particularly during their upward movement. As the godet rotates and carries the loaded pockets past their uppermost position, centrifugal and gravitation forces act on the liquid within the pockets causing the same to discharge therefrom in. approximately a radial direction.

While it is essential in the method illustrated in Fig. 1 that the godet it! be provided with teeth that are canted forwardly in the direction of rotation, the godet 12 may comprise a toothed section which is fluted, as shown in Fig. 2. The godets it and 12 have toothed sections for handling the strand while in a highly plastic condition since, for a few seconds after extrusion, the yarn is so tender that it is inadvisable to subject it to much tension. Wet yarn will tend to wrap on a smooth godet surface if it is not under a substantial tension and consequently fluted surfaces are provided in handling yarns at low tension. While passing over the fluted surfaces, the coagulation and regeneration of the yarn proceeds to such an extent that the yarn may be thereafter subjected to tension, such as applied during the stretching thereof. In the apparatus arrangements shown in Figs. 1 to 4, the yarn passes from the godets to a take-up system which-imparts sufficient tension to the yarn to accomplish a desired amount of stretching. It is desirable to stretch the yarn when it is positioned on the smooth godet surfaces since the stretching action is more uniformly applied than it would if the yarn were on the non-continuous periphery of a godet section comprising flutes or teeth. Furthermore, employment of smooth godet sections avoids the possibility f imposing impressions in the yarn, which may result if t. e yarn is stretched over the edges of the godet teeth. Such impressions tend to substantially reduce the denier of the yarn at the point of contact with the teeth and thus weaken the yarn, particularly as the yarn tends to stretch more at the sections of reduced denier. As illustrated, the maximum diameter of a fluted section of either of the godets 10 and i2, and the other godets shown in the drawing that have both-fluted and smooth sections, is approximately the sameas that of its smooth section.

The yarn passes from the hood 14 substantially free from coagulating liquid in view of the centrifugal action imposed there-on by the godets, and then passes through the trough 15 toward a pair ofcanted take- up rolls 19 and 20. These rolls serve to store a take-up length of yarn for liquid treatments while passing over the rolls and engage theyarn with sufficient friction to enable stretching thereof over the portion of its path extending between the points of contact with the godet 1t) and the roll 19. As the yarn passes from the godet 10, regeneration thereof has progressed to a stage that the yarn has sufi'icient tensile strength and the plasticity is sufiiciently reduced to warrant stretching. However, to accelerate and continue the regeneration of the material comprising the filaments "of the yarn, the yarn is passed through the trough 15, into whici a heated liquid is introduced through a tube 21. The liquid flows countercurrently with respect to the movement of the strand and is discharged into a receiver 22. The liquid used to promote regeneration maybe simply hot water, or a very dilute acid solution. If the latter is used, the acid solution'applied to the rolls 19 and 20 may be recovered, heated, and pumped through the duct 21 to the trough. In addition to accelerating the regeneration of the cellulose material of the yarn, the hot liquid in the trough 15 also plasticizes the green yarn thus facilitating the stretching and improving the manner of its application. Solution for promoting the regeneration of the material comprising the strand 9 may be supplementarily applied to a moreadvanced portion of the strand, i. e., that portion wound about the rolls 19 and 20. Preferably, these rolls are inclined, as well as canted with respect to each other, so that the windings travel from the lower ends of the rolls lengthwise thereof to the upper ends, and liquid applied to the rolls will then flow counter-currently to the movement of the strand while traversing the rolls. It is desirable to further the regeneration of the strand while traversing these rolls, and to accomplish this, heated liquid, such as that fed into the trough 15, is applied to the rolls by a duct 23 supported above the roll 19. The duct is disposed over a portion of roll 19, not far from the strand discharging end of the roll.

If desired, a sizing solution may be applied to the .final wraps of the strand through a duct 24, before passing the strand to a pair of drying drums 26 and 27. A stripper 28 may be mounted adjacent to the rolls 19 and 20 to engage one or more windings passing from one roll to the other to remove liquid from the strand before it reaches the portion of the roll 19 onto which the sizing solution is being applied from the duct 24. The speed of the drums 26 and 27 may be. regulated to obtain any desired magnitude of stretching or tension in the section of the strand passingbetween the draft rolls l9 and 20 and the drying drums 26 and 27. After being dried, the strand passes to a packaging device represented by a traverse guide 29 and the spindle 30. Figs. 3 and 4 illustrate apparatus which may be substituted for a portion of the apparatus illustrated in Fig. 1 to provide a slightly modified method. According to the arrangement shown in Fig. 3, fine streamsof filament forming material, areextruded from a spinneret 36 into a tube 37. A filament setting liquid, such as a coagulant is forced through the tube concurrently with respect to the direction of passage of the strand from a housing 39 which surrounds the spinneret. A coagulant or other liquid, is supplied to the housing through a duct 40. The resulting strand and the liquid are discharged into a container 42 which serves as'a collector for the liquid separated from the strand as it passes over a pair of stripping devices'43 and 44. 'The strand, ,with the coagulant substantially removed therefrom, passes onto a fluted section 46 of the godet 47. A godet 50, which may be connected in drive relationship with the godet 47 by means, such as the worm' drive system 48, is supported below the 'godet 47 and with its axis canted thereto. At least the godet 50 is inclined downwardly so that its smooth section '51 rotates within a bath 52 of heated regenerating solution maintained' atf the' desired level by an overflow means, such as a drainpipe 53. Additional application of the regeneratingisoluti'on is "implemented by shower devices 54 and 5, positionedover the smooth sections of godets 50 and 47 respectively. The devices 54 and 55, as well as an inlet tube 57 for the container 58, may be connected, as shown, t a system for supplying a regenerating solution comprising a pump 60 and a heat exchanger 61. Conventional automatic means (not shown) may be provided to control the operation of the heat exchanger to provide heated solution to the shower devices and the container 58 at an approximately constant temperature.

As shown in Figs. 3 and 4, the strand first travels over the fluted sections of the godets 47 and 50, then onto the smooth sections, and then passes onto a pair of inclined rolls 64 and 65 having their axes canted relative to each other. The rolls 64 and 65 are driven at a speed such as to stretch the strand to a desired degree as it passes from the godet 47 to the roll 64. Liquid treatments may be applied therebetween and/or to the windings of the strand on the rolls 64 and 65, and further treatments, such as drying and packaging of the strand, may be carried out in a manner as described with respect to the structure shown in Fig. l. The regenerating solution may consist of wash water collected from the rolls 64 and 65 in a container 66, and conducted to the exchanger 61 through a tube 67.

Fig. illustrates a godet 74, similar to the godet described with respect to Fig. 'l, sectioned through its axis to expose the contour of the teeth 73. Material extruded from a spinneret 69 emerges from the bath 70 as a bulky bundle of filamentary material constituting the strand 71. The bulk'iness of the strand is due to the low stage of coagulation and regeneration to which the filamentary material has advanced and also to the considerable quantity of liquid carried from the bath which surrounds the filaments. The filaments at this stage are skinlike casings of coagulated material enclosing liquid to plastic uncoagulated and unregenerated material. The windings of the strand 71 which extend around the godet 74 extend also around a guide 72 which may be employed in the manner of guides 80 and 84 of Figs. 6 and 7, respectively, to advance the strand lengthwise of the axis of the godet '74. As the strand 71 contacts the forwardly inclined teeth 73 of the godet 74, the liquid coagulant carried by the strand is pressed or forced from the strand and collected within the pockets 75 formed along the forward faces of the teeth. Fig. 5 is drawn to accurately reproduce the effect of the godet upon the strand 7 1 and the liquid carried thereon as revealed by photographs of actual operation. The liquid, as shown, is carried by the forwardly inclined teeth of the godet around to approxi inately the point at which the teeth start downward in their revolution about the axis of the godet. As the teeth travel downward, the liquid cntained in the pockets 75 is discharged under the influence of centrifugal force and the progressively increasing affect of gravitational force. As the teeth reach the lowest portion of their revolution, the liquid, collected within the pockets 75, is completely discharged.

Fig. 6 illustrates a godet 78 having teeth, similar in cross sectional contour to the teeth 73 of Fig. 5, which extend almost entirely lengthwise of the godet and constitute the entire peripheral strand-supporting section. A strand 79 is advanced longitudinally thereof by a guide 80. Fig. 7 illustrates a godet 81 having an annular section 82, which is fluted to form 'teeth such as shown in Fig. 5, and a smooth section 83 which may be employed to snub the strand when discharged toward a take-up device. A multi-finger guide 84 is used to traverse the strand lengthwise of the godet.

Fig. 8 illustrates apparatus that may be readily sub stituted for rolls 19 and 20 of Fig. l, or rolls 64 and 65 of Fig. 3, and ancillary equipment for carrying out liquid treatments. The apparatus of Fig. 8 comprises a conventional thread-advancing reel 90 having sets of interdigitating strand-supporting bars 91 and 92. The reel is driven by a motor 94 and enclosed within compartments 95 and 96. Barfles 97 and 98 separate the compartments to more eifectively carry out the separate applications of liquid treatment, such as sprayingsepar'ate portions of the reel with a regenerating solution and a sizing solution. For example, the section of reel within the compartment may be sprayed by a shower device 99 while a small stream of sizing solution is administered through a shower device 100 within the compartment 96. A winding of the strand may be caused to pass over a stripping element 102 to remove regenerating solution from the strand before it passes into the compartment 96. The compartments are provided with drainage ducts 104 and 105 for disposal or recirculation of the solutions collected in respective compartments. The reel is inclined, with its lower end-portion disposed within the compartment 95, receiving the strand. By such inclination, the liquid applied to the rolls moves countercurrently with respect to the reel and the strand passing thereover.

The invention is broadly concerned with the method of spinning yarns by a wet-spinning process wherein the coagulating or hardening fluid may be prevented from substantially mixing with the liquid applied in a succeeding treatment. The different liquids are effectively prevented from mixing by use ot'the godet systems hereinabove described comprising godets having fluted and smooth surfaces. Through the arrangement and operation of such systems in accordance with the methods of the invention, rapid conversion of a filament-forming material to a multiple filament strand having a desired chemical state is accomplished, with more efiicient use of spinning bath ingredients than possible with conventional apparatus. Moreover, the concentration and temperature of the spinning bath and other treating liquids actually in contact with the yarn are subject to precise control whereby the quality of the yarn may be controlled to a highly uniform level. A very important factor in the control of the concentration of the spinning bath through which the extruded filament-forming material is drawn, is the continuous and automatic liquid separation from the yarn, and the reuse of this diluted spinning bath solution which contains water produced by coagulation of the aqueous filament-forming material. The application of the spinning bath liquid or coagulant may be controlled to obtain a high degree of utilization of the ingredients which are discharged during the process and carry a relatively high concentration of by-products which may be reclaimed all the more economically.

While preferred embodiments of the invention have been shown and described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

The method of spinning a filamentary strand including the steps of extruding a continuous running strand into a liquid bath, drawing the strand upwardly through and out of said bath, passing the strand through a helical path about a rotatable godet having a serrated surface formed of circumferentially spaced teeth, said teeth each having a leading surface canted in the direction of the godet rotation to provide liquid receiving pockets between said teeth, advancing the strand through its helical path at approximately the same linear velocity as the portion of the strand drawn from said bath, collecting within said liquid receiving pockets substantially all of the liquid carried by those portions of the strand moving in an upward direction as the strand moves through its helical path to prevent said liquid from flowing along said strand in a direction opposite to its movement, discharging in a combined radial and tangential direction by the centrifugal and gravitational forces developed by said rotatable godet substantially all of the collected liquid onto only those portions of the strand moving in a downward direction as the strand is passed through its helical path, and drawing the strand from said godet at a linear yelocity greater thanthat portion of the strand drawn from said bath to place the same in tension.

References Cited in the file of this patent McLeIlan Sept. 18, 1945 UNITED STATES PATENTS 6 Proctor Aug. 17, 1880 Dixon July 13, 1909 Minahan Mar. 8,.1910 Johnson Mar. 23, 1926 Knebusch Aug. 31, 1937 10 Blount Dec. 5, 1939 Uytenbogaart Sept. 2, 1941 Moritz Apr. 18, 1944 Polak May 9, 1944 15

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