US2453332A - Process of treating yarn - Google Patents

Description

1943- F. R.' MILLHISER PROCESS OF TREATING YARN Filed Sept. 22, 1944 Patented Nov. 9, 1948 UNITED STATES PATENT OFFICE PROCESS OF TREATING YARN Frederick R. Millhiser, Richmond, Va., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application September 22, 1944, Serial No. 555,210

5 Claims. 1

This invention relates to improving the physical properties of viscose rayon yarn spun to a bobbin by the hot dip process. It relates, more particularly, to a process of treating viscose rayon yarn spun to a bobbin by the hot dip process to produce a yarn which can be converted to cord having highly improved resistance to fatigue.

One of the conventional processes for producing viscose rayon yarns, i, e. regenerated cellulose produced from viscose, is the bobbin process. According to such process, a solution of viscose is extruded through a suitable nozzle or spinneret into a coagulatin and regenerating bath, from which the filaments of regenerated cellulose are withdrawn and the yarn filaments leaving the bath are passed to a rotating spool or bobbin on which they are traversed and wound into a cake. Layer upon layer of yarn is permitted to collect on the bobbin until the accumulated mass forms a yarn cake of suitable size for dofiing and subsequent washing, purification or finishing treatment.

Recently there have been developed methods for spinning viscose rayon yarns of high tenacity according to which the coagulating and regenerating filaments are subjected to considerable tension and consequent stretching between the spinneret and the take-up bobbin and the yarn is wound on the bobbin under the same high tension at which it was spun.

United States Patents 1,901,007 and 1,996,989 disclose procedures for producing viscose rayon yarn of improved tenacity by passin the coagulated, partly regenerated filaments through a hot aqueous bath heated to 70" C. to 100 C. and, a

while the filaments are in contact with such hot aqueous bath, subjecting them to substantial tension and/or stretching. This procedure is known in the art as the hot dip process.

When the hot dip process was utilized in the bobbin process, there was produced a yarn of increased tensile strength. However, the improvement in yarn strength could not be converted to an improvement in tire cords produced from such yarn. This was so because such hot dip arn Was deficient, principally in transverse strength as reflected in fatigue resistance of cords.

An object of this invention is to produce a rayon yarn which can be converted to a tire cord having improved physical properties.

Another object of this invention is to provide a rayon yarn which can be converted to a tire cord having a high resistance to fatigue.

An additional object of this invention is to improve the physical properties of a viscose rayon yarn spun to a bobbin by the hot dip process.

A further object of this invention is to provide a method of treating viscose rayon yarn spun to a bobbin by the hot dip process whereby 2 it can be converted to a cord having a high resistance to fatigue.

Other and additional apparent hereafter.

The above objects are accomplished, in general, by unwinding a viscose rayon yarn, produced by the hot dip process, from the bobbin on which it was collected at the spinning machine and on which it was washed with water, and thereafter, while the yarn is still in the gel state, treating it with an aqueous fluid at a temperature above 90 C., the yarn during such treatment being under a tension of a magnitude not greater than 0.02 gram per denier.

The process is preferably carried out on the slasher so that the yarn immediately after treatment is slashed. In such embodiment of the invention, after washing the yarn on the bobbin, the bobbins are placed on a creel at the slasher. According to one procedure, a feed roll unwinds the yarn and feeds it onto a traveling belt which conveys the yarn through a steam chamber where it is heated and wetted. After leaving the steam chamber, the yarn is passed directly through the finish bath and into the slasher in the normal manner. The relative rates of speed of the belt and the feed roll are such that the yarn will, during steaming, be under substantially no ten- S1011.

According to another procedure, the yarn from the creel is fed into a steam chamber in the form of a warp sheet. From the steam chamber, the yarn passes directly through the finish bath and into the slasher in the normal manner. The steam chamber is located between two pairs of quetch rolls. The relative rates of speed of the quetch rolls are such that the yarn will be under a tension not greater than 0.02 gram per denier.

The nature of the invention will be more clearly apparent by reference to the following detailed description when taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic perspective view showing one form of an apparatus for carrying out the invention; and

Figure 2 is a perspective view of a modified form of apparatus which can be used for carrying out the invention.

Fig. 3 is a diagrammatic view of one form of apparatus for washing the yarn on a bobbin.

Referring now to the drawings wherein like reference numerals designate like parts, the reference numeral Ill designates a plurality of viscose rayon yarns in the gel state being continuobjects will become ously unwound from a corresponding number of bobbins 26 by a fluted feed roller 12 driven at a suitable speed by means not shown. The bobbins containing the yarn wound thereon at the spinning machine are appropriately mounted on a bobbin creel. The feed roller I2 feeds the'gel rayon yarns onto a continuous belt conveyer l4 travelin over a pair of rollers 16 and it! at the receiving and delivery ends respectively thereof. The roller H8 at the discharge end is driven. in any suitable manner by means not shown. The surface speed of the feed roller l2 and the surface speed of the belt is are such that the yarns 10 are in a relaxed condition on the belt l4 and under substantially no tension. Intermediate the delivery and discharge end of the conveyor Hi, there is a steam chamber, generally designated by the reference numeral 20, through which the conveyer l4 passes at least during its upper flight. Steam is continuously introduced into the steam chamber through the inlet 22, the steam passing from the steam chamber through the outlet 24. The size of the steam chamber and the rate of travel of the conveyer M are such that, when the yarns on the conveyer pass through the steam chamber 20, they will have been subjected to the steam treatment for the desired period of time. The yarns it, after the relaxing treatment, are passed directly into the slasher in the normal manner.

In the apparatus shown in Figure 1 and described above, the yarns are supported on a traveling surface during the relaxing treatment. The invention is not restricted to the use of such an apparatus. If desired, the yarns in the form of a warp sheet of threads may be subjected to the relaxing treatment on the run, and an apparatus for carrying out such procedure is shown in Figure 2.

Referring now to Figure 2, a plurality of rayon yarns in the gel state are unwound from a corresponding number of bobbins on which the yarns were wound at the spinning machine, and constitute a warp sheet of yarns, which passes through a steam chamber 32 positioned between two pairs of quetoh rolls 3@ and 36. Steam is introduced into the steam chamber 32 through the inlet 38 and passes therefrom through the outlet 40. The peripheral speeds of the quetch rolls 34 and 3B are such that the warp sheet of yarns is maintained therebetween under a tension, the magnitude of which does not exceed 0.02 gram per denier. The quetch rolls 36 also serve to feed the yarns to the slasher.

The following examples are given to illustrate the specific details of the present invention, it being understood that the details as set forth in these examples are not to be considered 1imitative of the invention, and the proportions are by weight:

Example I Cotton linters viscose, containing 7% cellulose and 6% caustic and ripened to a salt (sodium chloride) index of 5.2, is extruded into a coagulating and regenerating bath containing 8.0% sulfuric acid, 22.0% sodium sulfate, 0.7% zinc sulfate and 5.0% ferrous sulfate to form a yarn of 1100 denier-480 filaments. The bath is maintained at a temperature of 52 C., the yarn being passed around a plurality of roller guides so arranged as to provide a bath travel of 130 and impart to the yarn a spinning tension of 0.96 gram per denier. The yarn is then passed through a second bath containing water and maintained at a temperature of from 90 C. to 100 C., constituting the hot dip bath. The yarn is given a bath travel of 9" in the hot dip bath and subjected totension so as to stretch the yarn 17%. The yarn is collected on a bobbin at a wind-up speed of 3600 per minute and at a wind-up tension of from 100 to 1,000 grams. After a cake of app r. u L) priate size has been formed, the spun yarn is washed free of acid and salt while on the bobbin with water at 55 C. As shown in Figure 3, the yarn l0 may be pressure washed on the perforated bobbin 2G with the washing liquid coming through the conduit 28 to the perforations 30 and then through the yarn. Sufiicient pressure is applied at 32 to seal the bobbin. As shown in Figure 1, the washed yarn is talren oii the bobbin held on support 3d. The yarn is passed through a guide 36 and then in the path indicated. The washing step described may be replaced by any of the other conventional washing procedures. The yarn from the bobbin is transferred to a tray where in a relaxed state it is wetted out with water and after wetting, while maintained under substantially no tension, is subjected to a steam treatment for about 15 minutes, whereby the temperature of the wet yarn is raised to about 100 C. Thereafter, the yarn is slashed in the well-known manner.

Example II A plurality of bobbins of hot dip rayon yarn are prepared and washed free of acid and salts, as described in Example I. The yarn is unwound from the bobbin and treated while in the gel state in the apparatus shown in Figure 1. During treatment, the yarn is under substantially no tension.

Example III A plurality of bobbins of hot dip rayon yarn are prepared and washed free of acid and salts, as described in Example I. A plurality of the gel yarns in the form of a warp sheet are subjected to treatment in the apparatus shown in Figure 2. During treatment, the yarns are under a tension of 0.018 gram per denier or less.

The steam in Examples II and III is wet steam at atmospheric pressure.

Though as shown by the examples, water and steam are preferred, the invention is notrestricted thereto. In general, any aqueous composition in which the liquor is predominantly water can be used. Finishing compositions, dilute caustic or alkali carbonate or alkali bicarbonate solutions, dilute solutions of wetting agents, dilute solutions of neutral salts, and cord-dipping solutions are illustrative examples of various aqueous fluids which can be used. Any finishing composition containing 60% to 99% or more of water can be used.

The other ingredients in'the finishing composition may include oils, fats, waxes, wetting agents, anti-oxidants and the like. In the case of an aqueous solution containing caustic, the

caustic content should be low, for instance, not

more than 1% or 2%. Sodium carbonate or bicarbonate solutions may be used of somewhat higher concentration. Any of the known wetting agents may be added to water or to aqueous solutions and generally will be of low concentration, for instance, less than 3% or 4%. The concentration of neutral salts in water may vary widely, say from a few percent to 30% or 40%, depending on the solubility of the salt. Likewise, the cord-dipping solution may be of any known nature and concentration so long as it is preponderantly water. The cord-dipping solutions of Tippetts, Serial No. 493,228, issued as U. S. Patent No. 2,419,922, may be used.

The treatment with the aqueous fluid above C., and particularly steam, afiects primarily the tensile and loop strength Of the yarn as well as the bone dry strength and fatigue of the cord. In general, the effect is to decrease tensile strength and increase loop strength, at the same time increasing elongation. The oven dry strength and the conditioned strength of the cord are increased by the treatment. However, the most outstanding effect is on fatigue. regard, the improvement is of the order of 50% for a yarn spun to the bobbin with low tension and 300% for a yarn spun directly to a bobbin under high tension.

The following tables show the physical properties of cords produced from viscose rayon yarn spun by the hot dip process and collected on a bobbin, which yarn was treated as described in Example I for minutes, and cords produced from viscose rayon yarnspun by the hot dip process and collected on a bobbin and without treatment of the yarn:

AYarn wound to the bobbin at 200 grams tension Treated Untreated Slashing Conditions:

Stretch, per cent Quetch tension, grams Yarn Properties:

Denier Dry tenacity, g. p. d Wet tenacity, g. p. d Loop tenacity, g. p. d Dry elongation, per cent Wet elongation, per cent Loop elongation, per cent Wet contraction, per cent Cord Properties (1100/2 Construction) Conditioned to 12% moisture:

Denier 2 4 Tenacity, g. p. d Elongation, per cent at 10 lb. oad Elongation, per cent at break Oven-Dry:

Tenacity, g. p. d Elongation, per cent at 10 lb. load Elongation, per cent at break Fatigue rating, per cent Twist:

Single, T. P. I... Ply, T. P. I

B-Yarn wound to the bobbin tension grams Treated Untreated (I -Yarn wound to the bobbin at 1000 tension grams Treated Untreated Loop strength in grams per denier is the force in grams necessary to break one or both of two In this.

. properties.

6 v interlocked loops of yarn divided by twice the denier of the yarn. The loop strength is measured in grams on the same type of machine used for measuring dry tenacity, the break always occurring at the point of contact of the two collapsed, interlocked loops. Resistance to fatigue is measured by the time expressed in hours which a ribbon of cords made up from a given number of ends of the same type of cord can withstand alternate elongation and relaxation before complete rupture. The elongation and relaxation of the cord are accomplished by mechanical means under conditions designed to make the test as reproducible as possible. A conditioned cord is one which has been conditioned for at least 24 hours to a moisture content of 12%. An oven-dry cord is one which has been dried in a drying oven kept at 105 C. In determining the physicals of an oven-dry cord, the latter is tested immediately upon removal from the oven and before any substantial regain in moisture takes place.

Example I sets forth a specific coagulating and regenerating bath in the process of producing viscose rayon yarn spun to a bobbin by the hot dip process. The invention is, however, not restricted to such specific coagulating and regenerating baths. A coagulating and regenerating bath which contains 11% sulfuric acid, 23% sodium sulfate, 4% glucose and 0.85% zinc sulfate may be used. Similarly, the coagulating and regenerating baths disclosed in U. S. Patents 2,347,- 883 and 2,347,884 may be used.

The hot dip bath, instead of being water, may be aeidulated water or a viscose regenerating bath of the same or different composition-as that into which the viscose is initially spun. Optimum results are obtained when the hot dip bath is maintained at a temperature of about C. to C., so that stretching will take place in the yarn that is not below 85 C. at the region and time of stretching, although excellent results can often be obtained at much lower temperatures, such as at 75 C. or thereabouts. The stretch in the hot dip bath may be from 15% to 60% depending on the particular type of spinning arrangement.

In the examples, a specific tension and time of treatment are set forth. In general, the tension of the yarn being subjected to the steam treatment is of a magnitude which does not exceed 0.02 gram per denier. The time of treatment has generally been of the order of 10 to 15 minutes, although it is indicated that the desired result can be obtained by much shorter times of the order of one second if the proper high temperature is attained in that time.

The invention provides a process for producing viscose rayon yarns of improved physical Yarns produced in accordance with this invention possess not only a high tenacity and a good elongation, but also an improved and increased loop strength. Cords or plied structures prepared from the yarns of this invention have a satisfactory tenacity, elongation, and possess a greatly improved resistance to fatigue. These improved yarns are therefore eminently suited for use in the textile arts, and particularly in the reinforcing of rubber articles such as tires.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited thereto except as set forth in the appended claims.

i mclaim:

13 A process" for substantially improving" the ""physical properties" of hot dip multifilament vis- Verted to a tire cordhaving .high'resistance to atigue,which comprises washing said yarn while o'n the' bobbin, whereby said yarn is washed'acidree' at constant length; unwinding the'yarmand i treating the unwoundgel yarn with .an aqueous on 'the bobbin whereby said yarn is washedacid fre' at constant length, unwinding' the yarmand steaming the unwound gel-yarn While said gel yarn is under a tension notgr'eaterthan 0.02 gram per denier.

3; Acprocess for substantially improving the physicalprop'erties ofhot dip multifilam'ent viscose' rayon yarn wound up at the "spinning ma- S -Chine on a bobbinwh'ereby the-yarn can be converted to a tire cord-having high resistance to 6 fatigua'which comprises washing said yarn while" on'the bobbinwhe'reby said yarn is Washed acidfree at constant length, unwinding the yarn, and treating the unwound gel-yarn with an aqueous 'fluicl-a't'na temperatureabove 90 C. While said gel =yar"n is under substantially no tension.

4; A process for substantially improving the 1 r physical properties of hot dip 'multifilament: viscose rayon yarn wound-up atthespinningama- -chine on a bobbinwherebythe yarn canJb'e'cQnverted' to a tire cord havingrhigh resistancev to fatigue, which comprises washing said yarnwhile on the'bobbinwhereby said yarn is washed'a'cidfree at constant length, unwinding the yarn; and treating the unwound gel'yarn with wet steam While said gel yarn is under substantially no tension.

5; A- process for: substantially improving =the physical properties of hot dip multifilament Niscose rayon yarnwoundup at" the spinningmachineona bobbin whereby the yarn-can'becoin 'verted to a tire cord havingh'igh r'esistanceto fatigue, which comprises washing s'aid yarn while on the bobbin whereby said yarn iswashed' acidfree at constant length, unwinding a plurality of yarns from a plurality of'bobbins to form a warp sheet, and treating said warp sheet of gel yarns with wet steam while said gel yarns are under a tension not greater than 0.02 gram per denier.

FREDERICK R. MILLHISER.

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

UNITED STATES PATENTS Number Name Date 2,159,097 Moncriefi et a1. May 23, 1939 2,298,868 Catlin Oct; 13, 1942 2,340,377 Graumann et a1. Feb. 1; 1944 2,346,208 ConaWay. Apr. 11, 1944 2,377,434 Lyem June 5, 1945 2,388,742

H111 et al. NOV. 13, 1945

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