US2369191A - Manufacture of rayon - Google Patents

Description

MANUFACTURE OF RAYON Original Filed latch 1, 1939 '4 Sheets-Sheet 1 oms man nu vaca/ou d .1; Diner-Arrow cnwmsrsmurmv Pipe/vrp 1v wlan/or marx JUJJTMf/HL Jffm/IING Mone/sp Ma Feb. 13, 1945. Q THURMQND 2,369,191

KARUFAC TURB OF RAYON Oiginl Filed Burch 1, 1939 4 Sheets-Shoot `2 Fb 13 1945- G. l. rHuRMoND 2,369,191

nnunctun oF muon Original Filed llaroh 1, 1939 4 shuts-Shut 3 MQ/KWMM Feb. 13, 1945. G, THURMQND 2,369,191l

MANUFACTURE OF RAYON Original Filed March 1. 19259 4 ShsetsPShoet 4 El@ Gi@ C9@ q@es M9@ 5GB@ S? @Q ammo@ @l 6 zlerilwmaad www Patented Feb. 13, 1945 2,369,191y MANUFACTURE or RAYON Guben I.n 'rum-mona. Ashevme, N. c., signor to American Enka Corporation, Enka, N. C., a corporation of Delaware application March 1, 1939, Serial No. Divided and this application August l'iglnal 3l, 1942, Serial No. 456,805

6 Claims.

The present application is a division of my application Serial No. 259,261, filed Mar. 1, 1939.

This invention relates to a process of and system for producing a. strong yarn or thread of synthetic filaments and to the treatment of yarn or thread in a manner to preserve the properties thereof when formed into a cable of the type normally used in the manufacture of pneumatic tires, hose, belting or reinforcements for molded and cast plastic materials in general of either natural or synthetic origin. More specidcally the invention contemplates the formation of improved artiilclal threads or filaments formed primarily of viscose which have an unusually high tenacity and low elongation.

In the manufacture of pneumatic tires and generally similar flexible rubber articles it has long been the custom to utilize cotton cords for the reinforcement thereof. The substantially universal use of cotton cords in the manufacture of tires has been due primarily to the fact that such cords are not affected by heat and moisture to `a prohibitive degree and that when they are formed into strands twisted in a definite manner they have the required degree of resiliency, flexibility and tenacity. However, during recent years many tests have shown that cords formed of rayon may be utilized in tires and like construc- -tion with even greater eiiectiveness than cords produced from cotton. Nevertheless, the substitution of rayon cords or cables for cotton cords in the manufacture of products of the type indicated has been delayed for numerous difficulties were encountered which had to be more fully overcome before rayon cords were suitable for extensive commercial adoption.

In view of the research and other activities of the manufacturers of tires, belts and allied products there is at present a demand for high quality rayon threads and yarns at a cost somewhat comparable with cotton, and this demand will undoubtedly increase rapidly as yarns are produced which have a greater strength and lower elongation and when cables formed therefrom have higher flexing tests and adhere satisfactorily to rubber. Customarily tire cords are formed in three, separate twisting operations, the basic threads which are termed yarn comprise a plurality of small filaments twisted together. A plurality of yarns are twisted together or lplied to form a structure known as a ply or intermediate strand and plies thus formed are twisted with other plies to form a cord or cable. It has been determined that the properties of the cable are dependent in part upon the degree of twist at each stage in the formation thereof. Preferably the yarn has a very low degree of twist.

In connection with the use of rayon in the production of cables for use as reinforcements in tires, belts and the like, the properties of the individual laments and of the slightly twisted yarn determine to a substantial degree the final properties of the cables or cords. While the strength per unit weight and elongation of the cable or cord may be marke y impaired by improper twisting at its various stages of formation yet the ratio of corresponding values for iliaments and cords will be very nearly constant for a given method of twisting.

In the manufacture of pneumatic tires, cords are impregnated with and covered by rubber which is then vulcanized and the strength of the tire walls is dependent to a large extent upon the properties of the cord imbedded therein. It`

is clear that a strong cord is required for use in tires. However, disadvantages other than those naturally resulting from weakness of the ber arise from the use of inferior cords even when formed of high quality fibers and the reasons therefor are not so readily apparent. If there is any tendency on the part of the cord to alter its length due to its original inferior qualities or because of deterioration or aging, the bond between adjacentrcords and between the cord and rubber may be ruptured to such extent as to render the tires practically useless. Neverthe less, the cord must have a substantial resiliency in order to withstand the strains normalhr imposed by reason of the pneumatic pressure within and of mechanical shocks applied to the exterior of the tire casing. Rayon threads and cables known prior to this invention do not possess `a suitable combination of high tenacity. resilience and low degree of elongation to adapt them for use in bodies formed from plastic compositions, such as tires, belts, and the like.

'Il'iis invention contemplates the provision of a superior type of artificial filaments and yarn formed thereof, which overcomes the diiilcultles referred to above and which have a high tenacity and other properties very desirable in the production of cords for the fabrication of pneumatic tires and the like. It has as a further object the provision of a process for the formation of filaments and yarns of uniform properties.

Additionally the invention contemplates a process of and a system for producing a stronsr and extremely low elongation artificial yarn, wherein the freshly formed maments are stretched, for example, up to the breaking point,

tion with the accompanying drawings wherein:

Figure 1 is a flow sheet setting forth the important steps of one complete interrupted process conducted in accordance with the invention;

Figure 2 'is a diagrammatic view of an apparatus which includes a twisting device used in one step of the alternative interrupted process of Figure 1;

Figure 3 is another modification shown diagrammatically of the invention wherein the major stretching operation takes place between driven rollers and during washing; and

Figure 4 is a schematic view or a plurality of packages being unwound from a creell passed through a slasher and collected on a beam.

In referring to the drawings in detail with particular reference to Figure 1, it will be seen that the present invention when applied to the production of viscose yarn comprises generally the preparation of a viscose spinning solution of alkali and cellulose, the latter preferably comprising at least 25% of cotton linters. The solution is then aged, filtered and thoroughly deaerated. Such deaeration of the viscose is usually accomplished under vacuum, in which event the deaeration step is preferably practiced by subjecting the viscose solution to pressures abnormally low as compared with known technique for an abnormally prolonged period of time. For example, a vacuum below 20 mm. may be desirable. The spinning solution thus treated is then delivered to spinnerets through corrosion resistant and non-contaminating conduits, spun into a. coagulating bath and the yarn composed of a number of nlaments is thereafter stretched a plurality of times. In the spinning arrangement shown in Figure 3, the yarn is only given a slight stretch between the spinneret and first godet, but by virtue of the washing action in the second bath which is only slightly acidic, a very much greater stretch can be obtained between the two godets than has heretofore been possible. When the yarn is stretched initially up to its breaking pointv while in acid condition and then is washed and again stretched up to its breaking point while in a moist and substantially acid-free condition it will have a very high tensile strength. and

low degree of elongation. However, filaments which are stretched to a lesser degree during etiher of the stretching steps or both will nevertheless be suited for use in tires and they will -have substantially uniform properties throughout their lengths.

It has also been determined that very enicient results may be had if the filaments are stretchedv but once providing a high degree of stretch is imparted thereto. This is particularly true if the stretching step is conducted during. or subsequent to, the partial washing of the filaments and while they are still in a plastic state.

More specifically, as will appear from a consideration of Figure 1 of. the drawings. very nigh quality filaments are obtained by the utilization of o. viscose solution which contains about 7.4% cellulose by weight and an equal amount of sodium hydroxide. Although the viscose solution employed according to this invention: is characterized by a content of cellulose substantially equal to the amount of caustic employed therein, the proportions may be varied within rather wide limits with resultant loss of but some of the benefits of the invention. After the preparation of the viscose solution it is subjected to high vacuum deaeration for a. prolonged period. The deaerated solution is then aged or ripened. Preferably it is ripened to or above 11B/2 ammonium chloride index. During the aging period the viscose solution is filtered in a filtration appar ratus composed of materials resistant to attack by components of the solution. A filter press may be utilized for this purpose. the fram of the press and other parts which come in contact with the solution being formed of, or covered with, nickel or other suitable material which will not contaminate the solution undergoing treatment. After the viscose solution has been properly ripened and it has been filtered it is passed through conduits simimrly foi-nieu or uned with mm-` contaminating material and it ls delivered to spinnerets through which it is extruded into a spinning or coagulating bath.

The filaments thus formed are then stretched and further treated to provide a yarn having a high tensile strength, a low degree of elongation particularly suited to the formation of tire cords and one which has substantially uniform properties throughout its length.

In general the spinning bath is of somewhat conventional nature except with respect to the magnesium content and as hereinafter specified. Other components dissolved therein may include sulphuric acid, sodium sulphate, ammonium sulphate, zinc sulphate and other salts when desirable. Such baths, as are known in theart. give considerable dimculty during the spinning opera.- tion by reason of the fact that when they are used solids tend to accumulate in the spinner-et orifices and impair the properties of the filaments. In order to produce a yarn` satisfactory for .general use frequent cleaning of the spinnerets was found to be necessary and this cleaning operation of the small orifices necessarily involves costly precision work. y However, this problem may now be substantially entirely overcome and a great improvement in the properties of the filaments produced will be had by spinning the filaments in the presence of a dissolved material of acetico-active nature.- Buch materials are discussed at length in United States Patent 2,125,031 to Polak, et al. For example. a small quantity (0.04 per cent by weight) of dodecyl pyridinium chloride dissolved in the spinning bath eliminates practically all of the irreguiaritieay and difficulties of spinning and permits a much longer spinning time free from the frequent interruptions heretofore encountered for cleaning the spinneret.

The contamination of the spinnerets to an ex aggerated degree has ben encountered when an ordinary viscose solution is extruded through gold-palladium spinnerets into a spinning bath of the typenoted above. The spinnerets become seriously ccmtaminated in a few hours and this incurs interruption of the spinning period with resultant time and production losses. However. the presence of 0.1% of dodecyl triethyl ammonium iodide in the spinning solution reduces the tendency toward clogging of the spinneret orifices to a remarkable extent.

The laments formed by the extrusion step are conducted through the bath and upon being withdrawn therefrom they are given a suitable stretch, such as for example from about 30% up to .the breaking point. The filaments are then again stretched while in moist condition from about up to the breaking point. Between the two stretching steps the filaments are preferably washed and desulphurized or at least they are partially washed since the intermediate washing step causes the filaments to be stronger and to have a lower elongation than when the step is omitted. It is surprising to note that by following such a procedure considerably more stretch can be imparted to the filaments than has heretofore been possible. A total stretch can be obtained that is substantially above 50% and it has even been determined that the filaments can be stretched more than 70% of their original length without breaking. Washing and desulphurizing of the filaments may be Laccomplished in several ways, one being shown in the flow sheet (Figure 1) of the drawings wherein the coagulated filaments are stretched and then wound upon a spool under reduced tension, whereupon the bobbin is washed by the pressurevacuum method and the moist filaments are then either twisted and stretched during a rewinding operation or they are merely stretched and not twisted. Cake spun yarn having been twisted during collection has to be stretched only.

The interrupted process permits the winding of a spool of freshly spun yarn under less tenspaced relation to godet wheel Il and it is rotated at a greater peripheral speed than is the first godet wheel, whereby, when the yarn is passed from the godet wheel il and is directed over and around godet wheel il one or more times, it will of necessity be stretched between the two godet wheels, the desired degree of stretching being controlled by the relative speeds of the godet wheels.

The filaments are then, passed from godet wheel I4 to and around idler il. whereupon they are passed to the temporary bobbin I0 where they are collected under reduced tension. It will be noted in the system as thus far described only one stretching is imparted to the filaments up to the time of collection on bobbin Il. Bobbi.n `|I is next subjected to a high-pressure. highvacuum washing and/or other treating operation in a bath I'I. Bobbin Il, after being treated. and while the filaments are still in a plastic oondition, is placed upon a stationary support and the filaments are drawn therefrom' and twisted.

, The filaments pass through guide i8 and then around'godet wheel il one or more times. and

they are then passed to and around godet wheel 20, after which they are delivered to bobbin 2i for collection in the usual manner. Godet wheels i9 and 20 are substantially the same as godet wheels Il and Il and the filaments are conducted'thereover in a similar manner. In order to effect a second stretching of the filaments as 4 they are passed betweenv godet wheels Il and 2l,

godet wheel .20 is driven in such a manner that sion than heretofore utilized and this facilitates easy washing of the yarn while in spool form. During the rewinding the yarn is wound in the usual manner. Ease oi' washing is an important feature of this phase of the invention. In this connection it should be noted that while the second stretching step may be performed before complete washing, such procedure then involves the washing of a tightly wound bobbin, but this is permissible because the package contains only a small amount of residual acid from the precipitating bath.

In referring to Figures 2 and 3 inclusive, the systems illustrated are constructed in accordance with specific features of this invention. Yarns having the characteristics suitable for use in the manufacture of tires and the like may be readily produced with Veither of the systems by fthe' proper preparation and handling of the spinning solution in the bath and by the control of the stretching operation. While artificial yarns other than viscose yarns may be produced by the methods herein disclosed with satisfactory results, it will sumce to refer to the apparatus illustrated when used in connection with the viscose process.

In the system shown in Figure 2, a spinneret III is connected to a feed pipe (not shown) through which a viscose solution properly prepared, deaerated and ripened, is delivered thereto. The solution is then extruded through the spinneret into a coagulating bath il of the type referred to above. and the yarn l2 formed of a number of filaments is drawn from the bath by a godet wheel il. The yarn is propelled by the godet I3 at the same speed as the peripheral speed thereof and the yarn .is led one or more times therearound to avoid slippage upon its surface. Another godet wheel Il is arranged in its peripheral speed is increased to the desied extent above the peripheral speed of godet wheel i8. In the event that the freshly spun filaments are collected in a centrifugal bucket, the cake is made up of already twisted filaments, in which case `it is only necessary to restretch and collect the filaments in a manner also shown in Figure 2. It is, of course, within the scope of the invention to dry the washed bobbin or cake spun package prior to the re-stretching operation. The dried package must then be rewetted before or during the second stretch. Thezwashed bobbin package i6 may even be satisfactorily restretched without twisting. the twisting step being conducted in a subsequent separate operation. When the package IB or IBa is restretched between the godets i9 and 20, a certain amount of drying will result, especially if `the twisting is simultaneously effected. If it is desired to completely dry the packages either in bobbin or cake form, a drying zone can be readily interposed between the last godet 20 and the take-up device 2i. It has been determined that such treatment will result in yarn having extremely uniform shrinkage properties throughout its length.

Referring now to Figure 3, the filaments il are extruded through spinneret Il into a coagulating bath Il and thence led one or more times around a godet wheel 22 whereupon the filaments are conducted to an idler roller 23 located in a wash bath 2l. This bath may be very slightly acidic in order to further coagulate the filaments while at the same time effect a substantial washing thereof. After the filaments leave the wash bath 24, they arewrapped one or more times around a godet wheel 25 rotating at a higher peripheral speed than godet wheel 22. This difference'in peripheral speed imparts the desired stretch to the filaments which taken in conjunction with `the initial stretch in bath Il, can be considerably greater than was heretofore pos- -uscd in theI production of cord, tires and the are then collected on a bobbin 26 or in a pot after first passing around a second idler roller 21.

It is apparent from the foregoing that in the present process in which a high stretch is only imparted at one stage, the threads may be initially collected under the desired .tension in acid condition, either partially washed or unwashed. After the complete washing and other aftertreatxnents have been eiected, the package is rewound at which time a multiplicity of such threads are given an additional stretch and dried on a slasher and finally collected at a common source such as a beam or the like (see Figure 4). Of course, if the initial package is washed and dried in package form, it must be rewetted prior to restretching and drying on the slasher.

The yarn produced by the utilization of either of the above systems in connection with the process of this invention has, as stated above. important application to the tire and related arts. An important step in the preparation of a tire cord for the purpose of preventing loss of strength due to the twisting of the cord corn-4 ponents involves the application of a finishing material to the yarn in at least one stage of the spinning operation. A softening agent which has no deteriorating eil'ect on the yarn is utilized as the finishing material. This is a highly important aspect of the complete process oi' this invention since it has been found that the employment oi' the nishing material will improve the ilnal strength of the cable by from to 50% by preventing substantial loss in strength of the yarn during twisting. Apparently, the employment of the nishing material permits the yarns and plies when twisted to assume a position of least tension andstrain and specific flexing tests have been made on cables formed of yarn twisted as hereinafter specified which show abnormally high flexing tests as compared to yarn otherwise similar but not finished in the same manner. Additionally, cables formed from yarns finished in this manner are smoother and more dense than similar cables formed of untreated yarns and the strength thereof .closely approaches the combined strength of the individual-yarns. A solution of Monopole Brilliant oil has been found to produce excellent results when used as a iinish for the yarn. However, various types oi' materials can be advantageously used for this purpose and sulphonated olive oil, sulphonated castor oil. emulsied glycerides su'ch as blown tea-seed oil, and lecithin have been round satisfactory. purpose may be stabilized by the addition thereto of a small 'amount oi' alkali such as soap and an anti-oxidant.

The finishing agent may be applied to the yarn as such or as a solution or emulsion with any suitable vehicle. Good eilects are obtained from the addition oi a finish during washing or immediate subsequenttothe washingstage. Howthe treating material to the with redrying prior to the gives excellent results.' It 0.3% oi' monopole oil based on the weight o! the dry yarn will provide one oi' the best concentrations for most purposes. Results which have been obtained indicate very clearly that softening agents are. much better than lubricating iinisheg in connection with yarns to be plied or plied and cabled and thug: mineral'oil finish has twisting of the yarn has been found that For example, a straight little or no etlect in conserving Sulphonated oil for this 'formed therefrom,

aseaiai the yarn to give a strong cable, while a softening agent yields improvements in strength running as high as 50% over cables formed from yarns not so nished. It would seem that such ilnishing of the yarn is essential for the production of a smooth, well-formed, compact cable which will have the maximum strength'obtainable from a plurality of twisted yarns.

It is of course desirable that the yarn be lubricated to some extent to prevent breakage or other damage during handling and if the softening agent does not impart suiilcient lubrication thereto, a suitable lubricant may be blended with the softening agent.

Tire cords and reinforcing cables and fabrics used in various bodies formed of plastic material may be prepared from rayon in the manner noted above with numerous not heretofore obtainable advantages. In addition to the points of superiority already noted, the tendency of rayon cord in tires to grow" in service is prevented or minimized by the use of the yarns of low elongation described above. It will be readily seen that the tire structure will be adversely affected or the tire per se enlarges if the yarns used in producing the reinforcing cables becomes permanently elongated during use of the tire.

To better set forth a comparison of the improvements of the various features of this invention the details of one specific process for/producing a rayon cable will be described without the additional stretch but with the conditioning operation and other novel features merely by way of exemplication. A soaking lye is first prepared from 18.3% alkali containing 0.6% or 0.7% hemicellulose. Alkali cellulose is next prepared and at least 25% of cotton linters is utilized withthe remainder of the cellulose being derived from wood pulp. The alkali cellulose is shredded in a normal manner for two hours and is subjected to an ageing temperature of 21 C. for approximately 5B hours. tentof 7.4% and alkali content of 7.3% is next and it is permitted tp mature or ripen to 12.3 ammonium chloride index whereupon the viscosity is approximately 40 seconds. The viscose is then extruded through a spinneret into a coagulating bath containing sulphuric acid. sodium sulphate, zi-nc sulphate and approximately 10% of magnesium` sulphate. The spinning bath is maintained at a temperature oi 43 C. to 45 C., and a higher temperature may be utilized if proper equipment tion problems encountered with the likely impairment tn the health of the operators. The laments thus formed are conducted from the bath -and have a stretch imparted thereto of 45% by passing the same between two godets, and thence to a spinning spool that has a takeup'speed substantially equal to the peripheral speed oi the second godet. This corresponds to the ilrst part of t e interrupted process. The spinning speed uti is 7l meters per minute, the yarn being 275 deniers and having diamants. Yarn thus produced u washed acid tree and then dried and it is finished by being further dried by the vacuum method. .A solution 010.6% Monopole Brilliant oil is caused to permeate the wound package and the package is subjected to dry vacuum to insure uniform distribution of the finish. The package is then additionally dried on the spinning spool. After being dried, the yarn is then twisted tour turns per inch. The yarn in this condition is ready for formation into cables and in tests which have been conducted to determine the Viscose having a cellulose conis available to avoid evaporaassale:

ilexibility' of cables formed from such yarn, five of the thus formed yarns were twisted together to form a ply or intermediate strand and three such strands were then twisted together to form a cable. The flexing or fatigue test oi' such a cable was 35,2'35 flexes before breaking and a cable similarly produced but in which the viscose was formed entirely from wood pulp without the inclusion of cotton linters and the coagulating bath did not have a high magnesiumcontent, a flexing test of 24,975 was determined, The same flexing test made with respect to a cable formed of yarns which were not finished with Monopole Brilliant oil or any of the other materials referred to above, had a flexing test of only about 900. The fatigue or llexing tests were conducted on a similar principle as that taught in an article by F. B. W. King and R. Truesdale, published in The Textile Recorder, May 15, 1923.

The other physical characteristics of the yarn are tabulated below in order to show by way of comparison the improved results obtained:

cords. ribbons,` foils, sheets or other products usually produced by extrusion or spinning. The invention has been described in detail in order that those skilled in th'e art may practice the same, but it is obvious that it is not to be restricted to the specific examples set forth.

` In using the expression up to the breaking point" throughout the specification and claims, it is. of course. intended to mean that the thread is stretched just short o f the breaking point.

What is claimed is:

l. A method of preparing freshly spun viscose rayon suitable for use in reinforcing rubber articles and-the like which comprises the steps of extruding a viscose solution into a coagulating bath to form a thread consisting of a multiplicity of filaments, withdrawing the thread from the bath and positively stretching the same while it is in at least a slightly acid condition and during partial washing, temporarily collecting the thread in package form under reduced tension, aftertreating the thread in package form including the Yarn Cable Dry Wet Dry elon- Wet elon- Elongastrength strength gatiou gation Strength tion Per een! Per cent Per cmi Preparecifromnormnlviscose.. l l 281 lf2 il 14 13 14 Prepsrec from normal viscose softening agent. 1 281 i112 11 14 1B 9. 4 gravures lwomfiiilxig taabggc examplel. iit. ...1. 31B 185 l2 16 19. 0 9

reparer a ve exam e una l 5%strctch g. 340 Il? 12.5 2i 8.5

The strength of the yarn is given in grams per 100 denier and the strength of the cable is given in pounds; in addition, the strength of both the yarn and cable was obtained by conditioning at 65% relative humidity.

Yarn prepared in accordance vwith the :above exampi but collected in a centrifugal bucket does not have ali/much strength or as low elongation as yarn collected on a bobbin. This is due to lack of tension present in the centrifugal bucket process. However, an additional stretch will cause the yarn to compare favorably with yarn collected on agbobbin. The following table indicates the properties of such yarn:

,The importance of stretching after washing and subsequent proper finishing to increase the cable strength, to prevent loss of strength during A cabling, and to obtain a cable of low elongation is obvious from the preceding examples.

In the utilization of this invention, it is extremely important that all apparatus, used in the preparation of the yarns, that contact with the substances entering into the formation thereof, be composed of a material which resists corrosion and which `will not contaminate said substances. It has long been known that porcelain, nickel and the like and stainless steel are suitable materials for use in constructing the filter pressesr, conduits, and the like or as linings or coating therefor.

It is to be understood that while `the discussion is generally directed tothe preparation of fila ments, it is intended 'to cover threads, yarns',

steps of washing and drying, unwinding, rewetting, and then simultaneously restretching and redrying the thread whereby the cumulative stretching steps provide a high tenacity thread and the drying under tension effects a low elongation thereof.

2. A method of preparing freshly spun viscose rayon suitable for use in reinforcing rubber articles and the like which comprises the steps of extruding a viscose solution into a coagulating bath to form a thread consisting of a multiplicity oi filaments, withdrawing the thread from the bath and positively stretching the samein acid condition and during partial washing, temporarily Ml 50 collecting the thread in package form under re- Dry wat Dry elon- Wt e101 duced tension, washing the said package substan mmh "ngh no am tially acid-free, drawing the thread from` the A package and drying the same under suilicient f 'mgsijj tension to again stretch the thread whereby the f 10- a 2nd stretch. 332 186 6 16 55 cumulative stretching steps provide a high tenacity thread an'd the drying under tension effects a low elongation thereof.

3. A method of preparing freshly spun viscose rayon suitable for use in reinforcing rubber articles andthe likewhich comprises the steps of extrudins a viscose solution into a coagulating bath to form a thread consisting o! a multiplicity of filaments, withdrawing the thread from the bath and positively stretching the same during Partial washing, temporarily collecting the thread in package form, completing the washing of said package, unwinding, rewetting, and then redrying the thread while restretching the same and drying the same whereby the cumulative stretch- 1118 steps provide a high tenacity thread and the drying under tension effects a low elongationy thereof.

4. A method of preparing freshly spun viscose` of extruding a viscose solution into a coagulating bath to form a thread consisting o! a multiplicity oi filaments, withdrawing the thread i rom the bath and positively stretching the same during partial washing above 50%, temporarily collecting the thread in package form, completing the washing thereof, drawing the thread from the package and finally, simultaneously restretching and drying whereby the cumulative stretching steps provide a high tenacity thread and the dry ing under tension effects a low elongationthereoi.

5. A process of preparing products containing thread of high tenacity and low elongation com prising preparing a viscose spinning solution, the cellulose content of which is derived from at least 25% cotton linters, extruding the viscose solution into an acid ccagulating bath containing metallic sulphates to form a thread consisting o! a multiplicity of illaments, drawing the thread from the coagulatingbath and positively stretching the same during partial washing substantially above 50%, collecting the stretched thread in package form. washing a plurality of such packages substantially acid-tree. finishing and drying the thread while eilecting an additional stretch on a slasher to reduce the elongation thereof and finally collecting same on a beam.

6. A process of preparing products containing thread of high tenacity and low elongation comprisms preparing a viscose spinning solution. the cellulose content oi' which is derived from at least 25% cotton linters, extruding the viscose solution into an acid coagulating bath containing metallic sulphates to form a thread consisting ci a multiplicity of filaments, drawing the thread from the coagulating bath and positively stretching the same during partial 'washing substantially above 5%. collecting the stretched thread in package form under reduced tension, washing the said packages substantially acid-free and drying the same, unwinding a pluralityI of such packages and rewetting and redrying the thread while eflectin an additional stretch on a slasher to reduce the elongation thereof and nnally collecting the thread, being passed from the slasher, on a beam.

GILBERT I. THURMOND.

CERTIFICATE 'OF CORRECTION.

Patent lic. 2,569,191.

February 15, 1914.5. i

GIIBERT I. THURI'IOND.

of the above numbered patent requiring corre ond column, lines 6B and 69, claim 5, strike out the words and before the comma in line 6T,

read with this coro the record of the case in the same and insert the same after "package" seme claim; and that the said Letters Patent should be rection therein that the same may conform t Patent office.

signed and and this 15th day of my, A. D. 19145.

(Seal) LeslieI Frazer Acting Commissioner of Patents.

It is hereby certified that error appears in the printed specification ctionas follows: Page 5, secand drying the of extruding a viscose solution into a coagulating bath to form a thread consisting o! a multiplicity oi filaments, withdrawing the thread i rom the bath and positively stretching the same during partial washing above 50%, temporarily collecting the thread in package form, completing the washing thereof, drawing the thread from the package and finally, simultaneously restretching and drying whereby the cumulative stretching steps provide a high tenacity thread and the dry ing under tension effects a low elongationthereoi.

5. A process of preparing products containing thread of high tenacity and low elongation com prising preparing a viscose spinning solution, the cellulose content of which is derived from at least 25% cotton linters, extruding the viscose solution into an acid ccagulating bath containing metallic sulphates to form a thread consisting o! a multiplicity of illaments, drawing the thread from the coagulatingbath and positively stretching the same during partial washing substantially above 50%, collecting the stretched thread in package form. washing a plurality of such packages substantially acid-tree. finishing and drying the thread while eilecting an additional stretch on a slasher to reduce the elongation thereof and finally collecting same on a beam.

6. A process of preparing products containing thread of high tenacity and low elongation comprisms preparing a viscose spinning solution. the cellulose content oi' which is derived from at least 25% cotton linters, extruding the viscose solution into an acid coagulating bath containing metallic sulphates to form a thread consisting ci a multiplicity of filaments, drawing the thread from the coagulating bath and positively stretching the same during partial 'washing substantially above 5%. collecting the stretched thread in package form under reduced tension, washing the said packages substantially acid-free and drying the same, unwinding a pluralityI of such packages and rewetting and redrying the thread while eflectin an additional stretch on a slasher to reduce the elongation thereof and nnally collecting the thread, being passed from the slasher, on a beam.

GILBERT I. THURMOND.

CERTIFICATE 'OF CORRECTION.

Patent lic. 2,569,191.

February 15, 1914.5. i

GIIBERT I. THURI'IOND.

of the above numbered patent requiring corre ond column, lines 6B and 69, claim 5, strike out the words and before the comma in line 6T,

read with this coro the record of the case in the same and insert the same after "package" seme claim; and that the said Letters Patent should be rection therein that the same may conform t Patent office.

signed and and this 15th day of my, A. D. 19145.

(Seal) LeslieI Frazer Acting Commissioner of Patents.

It is hereby certified that error appears in the printed specification ctionas follows: Page 5, secand drying the

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