US3310857A

US3310857A - Method of texturing secondary cellulose acetate yarn

Info

Publication number: US3310857A
Authority: US
Inventors: Robert J Loftin; Earl H Hartgrove
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1963-10-14
Filing date: 1963-10-14
Publication date: 1967-03-28
Anticipated expiration: 1984-03-28

Description

March 28, 1967 R. J. LOFTlN ET AL METHOD OF TEXTURING SECONDARY CELLULOSE ACETATE YARN Filed Oct. 14, 1965 3,310,857 METHGD F TEXTURING SECONDARY CELLU- LGSE AQETATE YARN Robert J. Loftin and Earl H. Hartgrove, Charlotte, N.C., assignors to Celanese Corporation, a corporation of Delaware Filed Oct. 14, 1963, Ser. No. 316,057 Claims. (Cl. 28-76) This invention relates to an improved textured or voluminous yarn. More particularly, the invention relates to a method for the production of an improved textured yarn of a secondary cellulose ester such as secondary cellulose acetate.

The texturing or voluminizing of yarns has been found useful for the purpose of increasing the bulk, and improving the hand, drape, covering power and loft of fabrics manufactured from such yarns. Thus, using such textured yarns, a fabric may be made having greater cover and bulk for a given weight of yarn than when untextured yarn is used, or less weight of yarn may be used to obtain a certain degree of cover and bulk.

In addition to the above advantages, fabrics made from textured yarns generally yie-ld greater comfort because of improved moisture absorption, have excellent esthetic appeal and dimensional stability as compared with fabrics made from untextured yarn, and have better resistance to fuzzing and pilling as compared with fabrics made from spun yarn.

Various difficulties have been encountered in utilizing textured yarns of a secondary cellulose ester such as secondary cellulose acetate prepared by methods used heretofore. Thus, it has been found in some cases that too large a portion of the bulk imparted to the yarn is lost during subsequent processing of the yarn and fabric. More over, the physical properties of the yarn such as the tenacity has often been found to suffer to too large an extent as a result of the texturing. In some cases, also, the bulk imparted to the yarn is not as uniform as would be desired.

It is an object of this invention to provide an improved textured yarn of secondary ester such as secondary cellulose acetate.

It is a further object of this invention to provide a method for the texturing of a continuous multifilament yarn of secondary cellulose acetate yielding a product having improved properties and avoiding or minimizing the foregoing difiiculties.

Other objects will be apparent from the following detailed description and claims.

In accordance With one aspect of the invention, a yarn of a secondary cellulose ester such as secondary cellulose acetate, is twisted, e.g., by a false twisting device such that it contains about 18 to 75 turns per inch; desirably, e.g., for 200 denier yarn, the twist is in the range of about 30 to 46, preferably about 41 to 45 turns per inch and most suitably about 44 turns per inch. While the yarn is in such twisted condition, it is fed to a temperature zone where it is heated to a temperature of about 170 to 200 C.; desirably, e.g., for 200 denier yarn, the temperature is in the range of about 170 to 190 C., preferably about 170 to 180 C. and most suitably about 175 C. The yarn is heated for a period of about 4.5 to 0.030 seconds; desirably, e.g., for 200 denier yarn, the period of heating is in the range of about 3.0 to 0.030 seconds preferably about 1.60 to 1.20 seconds, and most suitably about 1.41 seconds. The temperature zone is located on the yarn path before the point at which twist is inserted into the yarn, e.g., by a twisting device such as a false twist spindle. The twist is translated back along the length of the yarn in the direction of the incoming yarn until a point at which the twist is held in the yarn, e.g., by feed rollers or a snubbing 3,310,857 Patented Mar. 28, 1967 device. After leaving the temperature zone and twisting device, the yarn is advanced, e.g., by feed rollers, at a rate of about 99 to 109%, preferably about 102 to 108%, and most suitably, e.g., for 200 denier yarn, at about 107% of the rate at which the yarn is fed to the temperature zone, the latter value being alternately identified as a 7% underfeed to the advancing means, e.g., feed rollers, beyond the temperature zones and twisting device. The untwisted and now cool yarn is subsequently allowed to relax in an amount of about 0 to 30%, preferably about 3 to 20%; desirably, e.g., for 200 denier yarn, the relaxation is in the range of about 14 to 20% and most suitably about 14% before it is taken up on a yarn package.

The aforementioned steps may be accomplished by feeding the yam to the temperature zone and twisting device at a certain rate by yarn advancing means, e.g., feed rollers, which pull the yarn from a yarn source, e.g., one or more yarn packages. After the yarn leaves the temperature zone, it is advanced by second yarn advancing means, e.g., feed rollers, at a rate within the aforementioned ranges, e.g., of about 99 to 109%, of the rate at which the yarn is fed to the temperature zone and twisting device.

The yarn may be fed directly from the second yarn advancing means to yarn take-up means, e.g., one or more yarn packages, which take up the yarn at a rate of about to 70%, preferably about 97 to 80% of the rate at which the yarn is advanced by the second yarn advancing means; desirably, e.g., for 200 denier yarn, the take-up speed is in the range of about 86 to 80% and most suitably about 86% of said rate. These rates correspond to the rates at which the yarn is allowed to relax as given above and the 86% rate corresponds to a 14% relaxation rate accomplished by a 14% overfeed to the yarn take-up means.

Textured yarn produced as described above may have a degree of liveliness great enough to cause some difficulty in subsequent yarn handling. If it is desired to at least partially reduce the liveliness as part of the continuous texturing process, the yarn is not passed from the second yarn advancing means directly to the yarn take-up means, but rather is passed through a second temperature zone where it is heated to a temperature of about to 200 C., preferably about to 192 C. and most suitably, e.g., for 200 denier yarn, about 175 C., for a period of about 4.5 to 0.30 seconds; desirably, e.g., for 200 denier yarn, the period of heating is 1.60 to 1.20 seconds, and most suitably about 1.41 seconds. After passing through the second temperature zone, the yarn is advanced by third yarn advancing means, e.g., rollers, which advance the yarn at a rate of about 100 to 40%, preferably about 96 to 70% and most suitably, e.g., for 200 denier yarn, at about 86% of the rate at which the yarn is advanced by the second yarn advancing means. From the third yarn advancing means, the yarn passes to the take-up means where it is taken up at a rate within the range of about 97.6% to 107.9% of the rate at which the yarn is advanced by said third yard advancing means.

If the second temperature zone is not used, the liveliness of the textured yarn is preferably reduced by subjecting the yarn to a steam treatment at a temperature, for example, of about 170 to F. at near atmospheric pressure for a period of about 45 to 85 minutes. After the steam treatment, the yarn is preferably subjected to dry heat, e.g., at a temperature of about 170 to 190 F. for a period of about 5 to 30 minutes. The latter treatment may be accomplished, for example, by using external heating :means, e.g., electrical heating elements, while sucking the steam from the treating chamber which is not completely shut off from the atmosphere. Thus, hot air in eifect replaces the withdrawn steam.

It has been found that in the ranges set out above the temperature at which the yarn is heated while twisted, and the rate at which the yarn is advanced by the yarn advancing means just beyond the first temperature zone and twisting device are critical in obtaining a textured yarn of high or maximum bulk as indicated by crimp contraction. Moreover, said range at which the yarn is advanced by the yarn advancing means beyond the first temperature zone and twisting device, and the range set out above or the twist in turns per inch in the yarn which is heated, are critical in obtaining a textured yarn of high or maximum tensile strength.

The method may be further illustrated with reference to the drawing wherein continuous multifilament yarn '10 is taken from yarn supply package 11, passed through pigtail guide 13, passed around pigtail guide and broken end device 15 and advanced by rollers 16 (first yarn advancing means). The yarn is then passed through first temperature zone 17 and is twisted by false twist spindle 19 from where the twist is translated back to rollers 16. From false twist spindle 19, the yarnis advanced by rollers 20 (second yarn advancing means) from which the yarn may take one of two paths. If there is no need to reduce the liveliness of the yarn or it is desired to reduce it in a subsequent treatment rather than as part of the texturing process, the yarn takes path A, and is passed directly from rollers 20 to pigtail guide 21 and

guide bars

22 and 23 and is taken up by yarn take-up package 24.

If a yarn having a reduced degree of liveliness is desired directly from the texturing process, the yarn follows path B, and is passed through second temperature zone 26 to rollers 27 (third yarn advancing means) and thence to guide 21,

guide bars

22 and 23 and yarn package 24.

Whether the yarn follows path A or path B, the actual twist accomplished by false twist spindle 19 is substantially removed by the time the yarn reaches rollers 20.

The process may be used to treat untextured yarn having a total denier, for example, in the range of about 55 to 1000, an initial twist in the range of about to 7 turns per inch, and composed of about 3 to 300 filaments.

The false twisting device referred to above is preferably a high speed false twist spindle of any of various types known in the art, e.g., that described in Patent No. 2,990,674 of Stoll et al. The spindle preferably rotates at a speed, for example, in the range of about 20,000 to 500,000 r.p.m., and the twist accomplished by the spindle should be in a direction opposite that of the twist of the supply yarn. Any residual twist present in the initial yarn should be taken into account when operating the twisting device in accordance with this invention so that the yarn contains the desired amount of twist in the temperature zone.

The process may be used to texture yarn at a rate, based on the supply yarn, in the range of, for example, about to 400, preferably 30 to 100 yards/ minute.

To substantially maintain the bulk resulting from the above-described process, the tension on the textured yarn during subsequent processing is maintained as low and as uniform as possible. For example, it may be advantageous to maintain the tension on the yarn during coning within the range of about 0 to 8 grams, when the feed yarn has a total denier in the range of about 55 to 1,000. Moreover, when it is desired to ply yarn having a total denier of about 110 to 3,000 using a spindle speed of about 4,400 to 6,200 r.p.m. subsequent to texturing the tension above the feed rollers may be maintained, for example, in the range of about 3 to 30 grams for two ply yarn and about 5 to 45 grams for three ply yarn.

When plying yarn, it is preferable that the finished plied yarn be balanced, i.e., substantially torque free. This may be accomplished by plying yarns which have been textured in opposite twist directions.

The textured yarn of this invention is particularly suitable for use in knitted fabrics which may be produced using any of a variety of single and double needle circular knitting machines. Yarn tension during knitting is preferably maintained at about 3 to 5 grams and as uniform as possible. The yarn is preferably fed to the knitting needles by positive feed rolls to assist in maintaining tensions as uniform as possible. Woven fabrics may also be made from the textured yarn of this invention.

In accordance with another aspect of the invention, the bulk of a knitted fabric produced from the textured yarn produced as described above is more fully developed and fabric-stitch relaxation is obtained by tumble relaxing the fabric before any wet processing, e.g., finishing at a temperature of at least about F., preferably about to 185 F. for a period of about 20 to 30 minutes. This may be accomplished using a machine with a drum that alternately rotates clockwise and counter-clockwise for about 15 to 30 seconds in each direction. Before removing the fabric from the tumbler, it is advisable to cool to about 120 to 150 F., preferably about 140 F. with continued tumbling prior to removal from the machine to prevent setting any creases and wrinkles.

To improve the hand of the fabric and eliminate creases after tumbling, the fabric is preferably subjected to a steam processing step, e.g., after slitting so that it is in open width form. The steam processing step may be a decatizing step, e.g., a semi-decating step, wherein the fabric between two cotton interliners is rolled on a perforated drum, exposed to the atmosphere and equipped with a steaming and vacuum system. During decatizing, the fabric is contacted with steam at a temperature of about to 210 F. for a period of about 15 seconds to 2 minutes, preferably about one minute, followed by the application of vacuum for a period of about /2 to 4 minutes, preferably about one minute.

Alternative steam processing treatments which may be used instead of decatizing are steam calendering and steam framing. In these procedures, the open-width fabric in the absence of any cover fabric, is passed over a slot, e.g., about six inches wide from which steam is flowing. This results in the fabric being contacted with steam at a temperature of about 180 to 210 F. for a period of about 2 to 8 seconds. When treating full-fashioned garments, a steam table is used in a similar manner.

The texturing process described above may be suitably carried out on an initial yarn which is already colored. The coloring may be accomplished using procedures wellknow in the art by dope-dyeing, i.e., adding an appropriate dye to the solution of the secondary cellulose ester being dry spun to form filaments, or by dyeing the yarn package before it is subjected to the texturing process. Alternatively, the fabric formed from the textured yarn may be dyed, e.g., in a paddle wheel machine or winch. The dyeing of a yarn package or fabric may be carried out using .an aqueous solution of a disperse acetate dye, e.g., any of those listed in the Colour Index, Second Edition, on pages 1659 to 1752. The dyebath may contain, for example, about 0.1 to 10% by weight of dye and the dyeing may be carried out, for example, at a ternperature of about 65 to 85 C.

If desired, the fabric may be finishedv to modify its hand. For a soft hand, a cationic finish may be applied in an amount of about 0.25 to 0.5% based on the weight of the fabric, while for a stiffer and harsher hand, the fabric may be coated with a resin emulsion in an amount of about 0.5 to 1.0% based on the weight of the fabric. The fabric may then be dried, for example, on a reel or loop dryer after centrifuging to remove excess liquid.

The invention is further illustrated by the following example:

Example Referring to the drawing, a continuous multifilament yarn, dope dyed moss green and consisting of 32 filaments of secondary cellulose acetate having an acetyl value of about 55%, a total denier of about 200, and a twist of 3 turns of Z-twist per inch, is fed by rollers 16 to the first temperature zone, i.e., heater 17 and false twist spindle 19 at a speed of 26 yards/minute. False twist spindle 19 is operated at a speed of 44,000 r.p.m. which causes the yarn to contain a twist in the S direction between spindle 19 and rollers 16 of 43.8 turns per inch. Yarn containing such twist is heated to a temperature of 175 C. for a period of 1.41 seconds.

The yarn from false twist spindle 19 loses most of its twist and is advanced by rollers 20 at a speed of 27.9 yards/minute which is 107% that at which it is fed by rollers 16. This is equivalent to a 7% underfeed to rollers 20. The yarn from rollers 20 travels along .path A through pigtail guide 21 and guide

bars

22 and 23 to yarn take-up package 24 where it is taken up at a speed of 25 yards per minute which is 86% of the speed at which it is advanced .by rollers 20. This corresponds to a 14% overfeed to take-up package 24.

The textured yam wound loosely on package 24 is contacted with steam at 185 F. for 75 minutes in a steam box at atmospheric pressure. The yarn is then kept at the same temperature in a dry state for an additional 15 minutes by heating with electrical heaters while sucking steam from the steam box.

The textured yarn is coned using a start-up at 6 grams tension and continuous tension relief to compensate for increasing yarn speed. The tension is relieved to 4 grams for a 1 /2 to 2 pound package. No yarn lubricant is applied during coning.

A circular knit fabric is prepared from the textured yarn using a double needle circular knitting machine, maintaining yarn tension at 3 to grams and as uniform as possible. The yarn is fed to the knitting needles by positive tfeed rolls to assist in maintaining uniform tensions.

To develop the bulk, and relax the stitching of the fabric, it is tumbled in a hot air tumbler for 30 minutes at 175 F. in a machine with a drum which alternately rotates clockwise and counter-clockwise for 15-2O seconds. The fabric is cooled to 140 F. with continued tumbling prior to removal from the machine.

The fabric is slit to open-width form and is decatized by batching onto a perforated drum fitted with a steaming and vacuum system and open to the atmosphere with a cotton interliner fabric between each fabric of textured secondary cellulose acetate yarn. The fabric is steamed for one minute at 185 F. and is then subjected to one minute of vacuum, applied from the inside of the drum.

Use of the above procedure results in the production of a knitted fabric of high bulk and excellent hand, cover and loft.

The described procedure is carried out, except that the yarn from rollers 20 follows path B rather than path A and the steam treatment of the yarn on package 24 is omitted. The yarn is heated in temperature zone 26 to 175 C. for 1.41 seconds and is advanced by rollers 27 at a rate 86% of that at which it is advanced by rollers 20. The yarn is then taken up by take-up package 24 at the same rate as that at which it is advanced by rollers 27. After knitting and decatizing, a fabric product is obtained similar to that obtained when the yarn follows path A and is subsequently steam treated on the package, as described above.

Knitted fabrics made by the process of this invention are suitable for a wide variety of end uses. They are particularly desirable for the production of ladies garments such as dresses, sweaters, skirts and blouses.

The term secondary cellulose ester is used to define cellulose esters containing about 0.43 to 0.77 preferably about 0.50 to 0.67 hydroxyl groups per anhydroglucose unit in the molecule. The term secondary cellulose acetate further denotes cellulose acetates containing about 53 to 57%, preferably about 54 to 56% of acetyl groups calculated as combined acetic acid by weight.

The term secondary cellulose acetate yarn is used to denote yarns composed of 100% of secondary cellulose acetate and also yarns containing amounts, e.g., less than 50% weight, of other fibers, in particular synthetic thermoplastic fibers such as nylon, polyester, acrylic and cellulose triacetate fibers and non-thermoplastic fibers such as rayon and natural fibers, e.g., cotton, linen and wool.

Moreover, while the process is particularly suitable for the treatment of continuous multifilament yarns, it may also be applied to yarns spun from staple fibers.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

What is claimed is:

1. Process of texturing a secondary cellulose ester yarn which comprises:

(a) advancing said yarn from a source thereof at a first rate of speed through a temperature zone to a twisting zone;

(b) inserting a twist of from about 18 to turns per inch in the yarn, said twist being translated back along the yarn in said temperature zone;

(c) heating the .said twisted yarn in said temperature zone to a temperature of from about 170 to 200 C. for a period of from about 4.5 to 0.03 seconds;

((1) substantially untwisting the yarn and advancing it beyond the twisting zone at a second rate of speed which is about 99 to 109 percent that of said first rate; and

(e) taking up said untwisted yarn at a rate of about 100 to 70 percent of said second rate of speed.

2. Process according to claim 1 wherein the cellulose ester is cellulose acetate, a twist of from about 30 to 46 turns is inserted in the yarn; the twisted yarn is heated to a temperature of from about 170 to 190 C. for a period of from about 3.0 to 0.03 seconds; the yarn is advanced at a second rate of speed which is about 102 to 108 percent that of said first rate, and the yarn is taken up at a rate of speed which is about 97 to percent that of the second rate of speed.

3. The process of claim 2 wherein said yarn is a continuous multifilament yarn having a denier of about 200, a twist of about 41 to 45 turns per inch is inserted. into the yarn, and the twisted yarn is heated to a temperature of about 170 to 180 C.

4. A textured yarn produced by the process of claim 3.

5. A process comprising feeding a secondary cellulose acetate yarn to a temperature zone and a twisting zone, a twist of about 18 to 75 turns per inch being inserted into the yarn at the twisting zone and translated back into the temperature zone, heating the twisted yarn in said temperature zone to a temperature of about 170 to 200 C. for a period of about 4.5 to 0.03 seconds, substantially untwisting the yarn and advancing it beyond said temperature and twisting zones at a rate of about 99 to 109% that at which it is fed to said temperature zone, taking up said yarn at a rate of about to 70% of said rate at which it is advanced beyond said temperature and twisting zones, steam treating the yarn after take-up at a temperature of about to 190 F. for a period of about 45 to 85 minutes, knitting the yarn into a fabric, dry tumbling the fabric at a temperature of about 170 to 185 F., and contacting the fabric with steam at a temperature of about to 210 F. for a period to obtain a fabric of high bulk.

6. The process of claim 5 wherein said fabric is contacted with steam in a decatizing treatment for a period of about 15 seconds to 2 minutes followed by the application of vacuum for a period of about /2 to 4 minutes.

7. The process of claim 5 wherein said yarn is a continuous multifilament yarn having a denier of about 200, a twist of about 41 to 45 turns per inch is inserted into the yarn, and the twisted yarn is heated to a temperature of about 170 to 190 C.

8. A process of texturing a secondary cellulose ester yarn which comprises twisting said yarn such that it contains about 18 to turns per inch and subsequently untwisting the yarn, feeding the twisted yarn to a first temperature zone where it is heated while twisted to a temperature of about 170 to 200 C. for a period of about 4.5 to 0.03 seconds, feeding said yarn after it is substantially untwisted to a second temperature zone at a rate of about 99 to 109% that at which it is fed to said first temperature zone, said yarn being heated in said second temperature to a temperature of about to 200 C. for a period of about 4.5 to 0.03 seconds, advancing the yarn beyond said second temperature zone at a rate of about 100 to 40% that at which it is fed to said second temperature zone, and taking up the yarn at a rate of about 97.6 to 107.9% of the rate at which it is advanced beyond said second temperature Zone.

9. A process of texturing a secondary cellulose acetate yarn which comprises twisting said yarn such that it contains about 30 to 46 turns per inch and subsequently untwisting the yarn, feeding the twisted yarn to a first temperature zone where it is heated while twisted to a temperature of about to 190 C. for a period of about 3.0 to 0.03 seconds, feeding the yarn after it is substantially untwisted to a second temperature zone at a rate of about 102 to 108% that at which it is fed to said first temperature zone, said yarn being heated in said second temperature zone to a temperature of about to 192 C. for a period of about 1.6 to 1.2 seconds, advancing the yarn beyond said second temperature zone at a rate of about 96 to 70% that at which it is fed to said second temperature zone and taking up the yarn at a rate of about 97.6 to 107.9% of the rate at which it is advanced beyond said second temperature zone.

10. A process comprising twisting a secondary cellulose acetate yarn such that it contains about 30 to 46 turns per inch and subsequently untwisting the yarn, feeding the twisted yarn to a first temperature zone where 8 it is heated while twisted to a temperature of about 170 to 190 C. for a period of about 3.0 to 0.03 seconds, feeding the yarn after it is substantially untwisted to a second temperature zone at a rate of about 102 to 108% that at which it is fed to said first temperature zone, said yarn being heated in said second temperature zone to a temperature of about 175 to 192 C.

for a period of about 1.6 to 1.2 seconds, advancing the yarn beyond said second temperature zone at a rate of about 96 to 70% that at which it is fed to said second temperature zone, taking up the yarn at a rate of about 97.6 to 107.9% of the rate at which it is advanced beyond said second temperature zone, knitting the yarn into a fabric, dry tumbling the fabric at a temperature of about 170 to 185 F. and contacting the fabric with steam at a temperature of about to 210 F. to obtain a fabric of high bulk.

11. The process of claim 10 wherein said fabric is conntacted with steam in a decatizing treatment for a period of about 15 seconds to 2 minutes followed by the application of vacuum for a period of about /2 to 4 minutes.

12. A textured yarn produced by the process of claim 1.

13. A textured yarn produced by the process of claim 9.

14. A fabric produced by the process of claim 5.

15. A fabric produced by the process of claim 10.

References Cited by the Examiner UNITED STATES PATENTS 2,869,318 1/1959 Stucki 57157 3,029,591 4/1962 Scragg et al. 57157 3,041,813 7/1962 Enneking 57157 X 3,077,724 2/ 1963 Stoddard et a1. 5734 FOREIGN PATENTS 1,140,992 3/1957 France. 1,217,137 12/1959 France.

850,693 10/ 1960 Great Britain.

908,514 10/1962 Great Britain.

FRANK I. COHEN, Primary Examiner.

J. PETRAKES, Assistant Examiner.

Claims

10. A PROCESS COMPRISING TWISTING A SCONDARY CELLULOSE ACETATE YARN SUCH THAT IT CONTAINS ABOUT 30 TO 46 TURNS PER INCH AND SUBSEQUENTLY UNTWISTING THE YARN, FEEDING THE TWISTED YARN TO A FIRST TEMPERATURE ZONE WHERE IT IS HEATED WHILE TWISTED TO A TEMPERATURE OF ABOUT 170 TO 190* C. FOR A PERIOD OF ABOUT 3.0 TO 0.03 SECONDS, FEEDING THE YARN AFTER IT IS SUBSTANTIALLY UNTWISTED TO A SECOND TEMPERATURE ZONE AT A TRATE OF ABOUT 102 TO 108% THAT AT WHICH IT IS FED TO SAID FIRST TEMPERATURE ZONE, SAID YARN BEING HEATED IN SAID SECOND TEMPERATURE ZONE TO A TEMPERATURE OF ABOUT 175 TO 192* C. FOR A PERIOD OF ABOUT 1.6 TO 1.2 SECONDS, ADVNCING THE YARN BEYOND SAID SCN DTEMPERATURE ZONE AT A RATE OF ABOUT 96 TO 70% THAT AT WHICH IT IS FED TO SAID SECOND TEMPERATURE ZONE, TAKING UP THE YARN AT A RATE OF ABOUT 97.6 TO 107.9% OF THE RATE AT WHICH IT IS ADVANCED BEYOND SAID SECON D TEMPERATURE ZONE, KNITTING THE YARN INTO A FABRIC, DRY TUMBLING HE FABRIC AT A TEMPERATURE OF ABOUT 170 TO 185* F. AND CONTACTING THE FABRIC WITH STEAM AT A TEMPERATURE OF ABOUT 180 TO 210* F. TO OBTAIN A FABRIC OF HIGH BULK.