CA2177566A1 - Method and apparatus for heat-treating yarns and products prepared therefrom - Google Patents

Abstract

This invention is directed to a method and apparatus for heat-treating multifilament yarn, wherein the yarn is fed into a chamber having imperforate and perforate sections, and to the resultant yarn products. Hot fluid is forced through a wad of the yarn in the imperforate section of the chamber and vented through the perforate section. The device may be used to bulk and heat-set yarns, depending upon the operating conditions. Yarn products prepared from this process are especially suitable for making carpets having good texture retention and carpet bulk.

Description

WO 95116065 2 1 7 7 5 6 6 PcrluS94/1399S
MET}~OD A~D APPARAT~8 FOR IEEAT~ 7~ YARNg AND rKvDUu O PREPARED ~ r~; ~
B~ ~KVUNL OF TIIE ~ ~V~C.~lUN
Field of thc Invention The present invention relates to the treatment of yarns which may be ~-ubse~u~a1.Lly used to manuracture carpets and the like. More particularly, this invention 10 relates to a method of and ~alc.~ for heat-treating ply-twisted, mult;fil I yarns in a continuoUs operation, where the ply-twisted strands of yarn are bulked and heat-set in their twisted, plied oondition.
15 Descril~tion of the R~l~ted Art Yarn which is used as pile in carpets is typically prepared by cabling or plying together two or more singles yarns and heat-setting them in their plied condition. One method involves heat-treating the yarn in a batch 20 condition as a skein Or yarn. Another method involves treating the yarn in an array of loops on an extended horizontal Cullvt:yu~ belt passing through a steam-heated oven, such as a system ~m~f~ct~ed by Superba. Another method involves treating the yarn as 25 hanging yarn loops advanced along by carrier belts on a cantilevered horizontal mast through a hot air-heated oven, such as a system manuf actured by Suessen . Such methods require numerous --- on~ çol devices and a large amount Or floor space in a yarn treating plant, and they 30 do not lend themselves to a compact continuous process for unwinding, ply-twisting, bulking, heat-setting, and winding of the yarn.
There is a need f or a s; _ l; f; P-i process and apparatus rOr bulking and heat-setting ply-twisted yarn 35 that is compact and does not reguire a great amount of floor space. Such a system should also be readily matched in speed to upstream and downstream proce5sing ~
There is also a need for a process and apparatus that can operate over a wide range o~ conditions to provide both WO95116065 ~ 1 7 7 5 6 ~ PCTNS94113995 yarns suitable for making carpets having a highly textured appearance, and, in other instances, yarns suitable for making carpets having little or no teYture, d~rDn~;n~ upon the desired carpet style. There is also a need for a 5 single device having the ~lexibility to only bulk the yarns, or to bulk and ~ully heat-set the yarns, der~n~l i n~
- upon the operating conditions and desired product. There ls also a need for a device that treats the yarn in a uniformly relaxed state under no tension so that the yarn l0 can freely shrink and bulk uniformly.
The present invention provides such a device and methods for heat-treating yarns, along with the resultant yarn L~L~ U~LS.
8m~ 7V OF ~ E lNVli~...l~N
This invention i n~ C a tubular heat-treating apparatus comprising an elongated chamber having a yarn entrance end and an opposed yarn exit end, and having a fluid jet on the entrance end for introducing fluid into the chamber. The chamber has an imperforate first portion 20 adjacent to the ~11LLc.l.c~ end for collecting a loosely folded wad of yarn, a E~econd portion adjacent the exit end for containing a loosely folded wad o~ yarn, and a perforate third portlon int~ te the; _L~,L~Ite portion and the cont~; ~ portion ror venting the fluid 25 from the chamber. The imperforate first portion comprises at least 40~ o~ the length of the chamber. Preferably, there is a fluid ~et on the exit end of the chamber for i1,LL~,du. lng i~luid into the chamber. In another preferred e~bodiment, there is a perforate portion adjacent to the 3 0 entrance end of the chamber for introducing additional ~luid into the chamber. In another ~ ., the apparatus includes means to sense chamber ~ UL ~ at the entrance end and means to vary the feeding of yarn to the chamber based on the sensed ~Lt:~aUL~. A controller ~ay be 35 Used to vary the feeding in response to changes in the sensed ~L;:~aUL~.
This invention also includes a method of heat-treating a yarn comprising the steps of heating an extended length of yarn with a heated fluid; forwarding Wo 95~16065 2 1 7 75 ~ 6 Pcr/USs4/13s95 .
the extended yarn with a flow of the fluid into an enclosed tubular chamber having imperforate and perforate portions; collecting the yarn in loose Eolds within a first im}7erforate portion of the chamber; passing the 5 fluid through the loosely folded yarn to heat-treat the -yarn fi l ~ ; forwarding the loosely folded yarn through the cha7lber by means of a force ;mhAl An~ e between the heated fluid ~nd 7~riction acting on the loosely ~olded yarn; venting the heated fluid from a perforate portion o~
the chamber int - ~te the ends o~ the loosely ~olded yarn; cooling the loosely folded yarn in the chamber; and pulling the cooled, loosely folded yarn into an extended length to thereby unfold and extend the ~olded yarn. In a preferred omhor7.; ' ~ the method involves cooling the loosely folded yarn with a cool fluid passing through the loosely folded yarn in a second imperforate portion of the chamber. The cool fluid passe6 in a direction opposing the heated fluid to cool the yarn. In another ~ --nt, the method further includes heating the loosely folded yarn with a second fluid, passing the second fluid through the loosely folded yarn, and venting the second fluid through the pe'Lrol.lte portions in~ ';Ate the ends of the loosely folded yarn. The invention also includes a nylon BCF product made by this process which has a spec;75;c r-lec~ - mic:Lu;-L u~LuL~: as is evidenced by specific shrinXage characteristics.
In one: ~ 7- , a ply-twisted yarn is only bulked by passing the yarn through the above apparatus by the above method and collecting only a short segment of yarn under zero tension for a short time so that minimal heat-setting occurs. The bulXed yarn may then be suhsos!77O77tly heat-set by passing the yarn through a heat-setting device.
7R7~r7~7~ D~ , OF ~777 F~ FIGm~Q
Figure 1 shows a section view of the heat-treating device in a simple form.
Figure 2 shows a section view of an alternate f '-:~; L of the heat-treating device.

2 1 7 7 5 ~ 6 PCT/US94/13995 ~!
Figure 3 shows 2m PYpl odPd view of a; et useful with the device.
Figure 4 showæ a top view of four carpet samples having various textures made with yarn ~ essed through 5 the heat-treating device under different conditions.
Figure 5 is a plot of shrinkage force versus temperature for several yarn samples each treated dif f erently .
DE'r~Ttrn l~ES~ OF THE LNvb~ N
Figure 1 shows a simple version of the heat-treating device 10 of the invention. It consists of an elongated tube 12 that define6 an elongated chamber 14 with tapered ends 16 and 18 to which is attached a hot 15 fluid jet 20. The device includes some means to feed untreated yarn 4 0 to the device and remove treated yarn 41 from the device, such as nip roll pairs 24 and 26 respectively. Stationary guides, such as 15, 17, 2nd 19, may be provided to add a slight tension to the yarn and 20 guide 21 may be added to provide a long span to permit yarn vibration to exert a slight llntAn~l in~ force before the yarn reaches nip rolls 26. These guides are P~pee~Al ly usQful when multiple yarn ends are fed to the device and the ends must be separated after being treated.
25 A hot fluid is fed to jet 20 through conduit 50 from a hot fluid source 48. The flow of fluid from the hot fluid source 48 to the chamber 14 may be controlled by a fixed or variable flow control orifice 57. The tube 12 has a first chamber portion 28 for c~ ec~ ~n~ a loosely folded 30 wad of yarn and heating it, a second chamber portion 30 for containing the wad of yarn and cooling it, and a third chamber portion 34, between the first and second portions, for containing the wad of yarn, venting the heating fluid and stopping the heating . The f irst portion is an 35 ~ ~oL~te portion. The second portion i3 shown as an roLe-te portion, but it may alternatively be a perforate portion if it is desired to provide for flow of a fluid transverse to the chamber and wad to aid in W0 95116065 2 1 7 7 ~ 6 ~ PcrluS94113995 .
cooling the wad. The third portion is a perforate portion to allow venting of fluids.
The chamber 14 is sized to ~. te a loosely folded wad of the yarn being red in. As such, chamber 14 5 is preferably larger than twenty times the yarn ~ .r and could be as much as 50 to 100 yarn ~i; ers in average ~ gectional chamber .~ n, i . e . the diameter of the chamber Cor a cylindrical chamber. It should be large enough 80 that there are only a small lO number of folds per inch in the yarn folded therein. The first portion Or the chamber should comprise a Rj~nif~clnt portion of the length of the chamber since it is in this portion that the heating oi~ the yarn wad takes place by forcing the heated fluid through the wad and maintaining 15 the heat for a particular r~-si~l~nre time. Preferably, the fir6t portion of the chamber comprises at least about 40%
of the length of the chamber. The third portion, which is a perforate portion, will be less than about 20~6 of the chamber length. It is here that the fluid is rapidly 20 vented and heating to a yarn ~L~i L t _-~c.~u.~ is stopped. The second portion of the chamber must be long enough so the ne~-P~s~ry cooling takes place before tension is applied to the yarn, and long enough to provide 5-1ff;. 1~ t space for unfolding of the yarn wad into an 25 extended length before the wad end 68 reaches the upper tapered end 18. For instance, a length of at least about one chamber diameter from the end of the wad to the beginning of the upper tapered end may be desirable for unfolding. The total length of the second portion depends 3 0 on the mode of cooling used .
Figure 2 shows another - '; r L of the heat-treating device lO of the invention. It consists of an elongated cylindrical tube 12 that defines an elongated cylindrical chamber 14 with conical ends 16 and 18 to 35 which are attached a hot fluid jet 20 and cool fluid jet 22. The device in~ some means to feed yarn to the hot ~ et and remove yarn from the cool j et, such as nip roll pairs 24 and 26 respectively. Nip roll pair 24 is driven by motor 25. It is contemplated that the speed of W095/l606s 2 1 77566 PCT/US941139g5 the motor can be controlled by the operator or by controller 27 receiving a control signal from sensor 67 that senses thc chamber pL-6DUL~ Pb. A cool rluid is ~ed to jet 22 through conduit 62 ~rom a cool fluid source 60.
5 A ~irst hot i~luid is ~ed to jet 20 through conauit 50 ~rom a hot fluid source 48. It i5 contemplated that the set - point for the energy supplied to the hot fluid source 48 may be varied by the U~LatOL or by controller 27 receiving a control signal from sensor 71 that senses the wad ~ aLuLe T4 through the wall of tube 12. The tube 12 has an imper~orate first portion 28 for collecting a loosely ~olded wad of yarn and heating it, an imperforate second portion 30 for cr-nt~n;n~ the wad of yarn and cooling it, ~nd a peLruLate third portion 34 between the ~ir6t and second imperforate portions ~or containing the wad o~ yarn, venting the heating ~luid and stopping the heating. There is also a peLrurate ~ourth portion 32 that provideD ~or i~low o~ a second hot ~luid into the chamber 14 through conduit 51 ~rom æource 48. Perforate third portion 34 provides for flow of cool and hot fluids out o~
chamber 14. There may be a hood 35 surrounding tube 12 ad~acent perforate portion 34 ~or removing the ~luids that flow out through p~LroL~te portion 34 to m;n1m;~e ~oncl~nc~tion o~ rluid vapors on tube 12 and reauce convective heating of the second portion o~ the chamber by rising heated fluids vented at the third portion. The hood is in - ; r~tion with a vacuum source 37 via conduit 39. There are provided means of controlling flow of the cool and hot fluids, such as fixed or variable flow control ori~ices 53, 55, ana 57 in cool fluid conduit 62, hot fluid conduit 51, and hot fluid conduit 50, respectively . There may be a chamber 3 6 within a tube 3 8 surrounding a portion of tube 12 (such as the ~irst and fourth portions) which provides for heâting of the tube, either by providing a space for insulation to prevent heat loss, or by providing a space for circulation of a heated ~luid, such as the second fluid.
Figure 3 shows details of jet 20 which is useful in the device of the invention for forwarding and heating the WO 95/160G5 Z ~ ~ 7 ~ ~ ~ PCrNS94113995 yarn. The jet is operated at low jet pressure Pl tFlg 2) of from about 1. 5 to 10 psig, so it will not supply a high velocity stream of fluid that may disrupt the plurality of filaments in the plied yarn being forwarded and heated.
5 The physical characteristics of jet 20 (and ~et 22) are described further in U.S. Patent 3,525,134 to Coon. The jet assembly 20 consists of a body 76 and a detachable cover 78 having a hole 79 for passage of a bolt for fastening the cover to body 76. Yarn line 40 moves through passage 42. Conduits 44 and 46 supply ~ 8:,u~ ized fluid to passage 42. The conduits are both the same width, "do", and have a depth "dp" that is about 2 to 4 times the width "do" . The ~t ~stjuLized fluid is supplied to the pair of conduits 44 and 46 from source 48 through manifold 82 that includes ports 84 and 86. One of these ports may be plugged during operation to reduce f low to passage 42. The width "do" may be changed to also vary the flow to passage 42. The flow rate of fluid from source 48 may also be varied to change the flow to passage 42. The jet p~c~ are sized and the chamber ~s~uLa Pb is set 80 that a slight blow-back through the entrance end 43 of jet passage 42 occurs. This en~ures that no air is aspirated into the ; et and into chamber 14 to dilute the sllrP~-hP:!~ted steam therein.
Jet 22 in Fig 2 has a configuration similar to jet 20, and it is also operated at low ~)L-~S~U~e: P2 (Fig 2) of about 1. 5 to 10 psig for unfolding and cooling the yarn without disrupting the fll; Ls. Another ~et (not shown) may also be positioned on top of and abutting jet 22 and oriented in the same direction as jet 20. This additional ~et would be used to facilitate threadup of yarn line 40 through the device at st~lrtup ror each product; for threadup, there would not be any loosely y-tl.ercd yarn in the device and jet 22 would be turned off. An upwardly angled hole (not shown) in the direction of yarn travel may intersect conical end 16 and be sl~rP~ l ed with ~ _ ~ssed air to also aid in threading up the deviGe . A
wire could also be inserted through the j ets and chamber 14 and be attached to the yarn to pull it through for W0 95/1606~ 7 7 ~ 6 ~ pCI/US94/13995 ~
threadup. The device of Figure 1 could also be threaded up similarly.
The device of Fig 1 and Fig 2 may be used to heat-treat different types of yarn including multiple strand ply-twi6ted and single strand twisted yarns. The tQrm "ply-twisted mul~ i f ~ l L yarr.", is meant to include a yarn constructed by cabling together two or more singles yarns in a unidirectional or alternate bi-direti~,n~
twist direction with the twist reversals between alternations either bonded or l~hn~l~od Such yarns are fi~r~ r to those skilled in the art. The device of this invention may also be used to treat air-_~.Ldl~gled yarns for di~ferent yarn styling effects. Preferably, the ply-twisted yarn is r,.~rOc"~ of bulked continuous f ilament lS (BCF) yarns, but staple spun yarns may also be used. The BCF and staple yarn contain f ~ l Ls prepared from synthetiC th. L l~ctic polymers 5uch as polyamides, polyesters, polyolefins, and acrylonitriles. Polyamides, such as poly - Lhylene a~ir~ o (nylon 6,6) and polycaprolactam (nylon 6) are ~sror~l ly suitable.
In one ~ L, a ply-twisted, mUlt~ f ~ l L
yarn 4 0 enter~; the chamber 14 through j et passage 4 2 and conical ~nd 16. A first heated fluid i5 directed at an angle to passage 42 through slots 44 and 46 that are fed by heated fluid source 48 through conduit 50 similar to the jet device described in u.S. Patent 3,525,134 to Coon.
The heated fluid is preferably steam which is preferably sl~r~rhr~ted by source 48, or the heated fluid may be air heated by source 48. If air or saturated steam is used, - 30 the rP~ciclon~ e times and t~ ~c L~LuL,s to achieve the same heat-LL~:a~ L for a given product may be dieferent than when ''"l' ~ I o~1 ed steam is used. The heated fluid forwards the yarn through the conical end 16 and into the cylindric~l chamber 14. The angle 52 made with the yarn 40 and the velocity of the fluid are such that the f i l Ls in the yarn are not substantially disturbed or entangled in the mul~ fi l -- t. bundle making up the yarn.
The yarn is forwarded and rapidly heated so that the yarn regains any bulk that was previously imparted into the WO95/16065 2 t 7~6 PcrrUs94/~399s yarn. The forwarding velocity of the fluid must be low relative to the yarn velocity, so the forwarding tension on the yarn remains very low and essentially "ten~r nl ess"
bulking o~ the yarn can occur. The pressure Pb in the 5 chamber, resulting ~rom introduction of the hot fluid, acts on the end 66 of the wad to propel the wad through the chamber ~rom the first to the second portion.
Friction between the entire length of the wad and the walls of the chamber resists the propulsive force of the 10 pL~s~uL~, The speed of the yarn entering the device is det~nm~n~d by the speed of rolls 24, and the speed of the yarn exiting the device is det~-rm; n~d by the speed of rolls 26. Since some shrinkage is common during heat-treatment of many yarns, the speed of rolls 24 may be 15-20~ higher than rolls 26. Rolls 24 and 26 are ~Yr~rli~rry of means to feed and remove yarn to and from the device, but additional pro~ e~:s1n~ e~r~i~ L u~LL_~u and dc~ L~ t a~u of the device could alternatively provide these means. For instance, a two-~or-one twister made by the 2 o Volkmann Company could provide means to remove the yarn when the heat-treating device is inserted ahead of the winder on the twister.
Rererring to Fig 2, it has also been round advantageous to provide a second supply o~ hot rluid for 25 heating and propr~l 1 ing the wad Or yarn by adding another flow of hot fluid ~rom source 48 via conduit 51 through tube 38 to chamber 36 and then through perforate fourth portion 32 to chamber 14. This permits the addition of a large flow of hot fluid for heating the wad of yarn 3 o without having a high velocity stream . Ir the additional flow had to go through the ~et 20, it would increase the ~low velocity and detri~ 1 ly entangle and tension the yarn f ~1 i ~ . To ~urther ensure the flow o~ additional hot fluid does not entangle the yarn as it is deposited in 35 loose folds, the pelL~Lte fourth portion may be positioned away from the yarn entrance end of the chamber;
and may be positioned just beyond the end 66 of the wad where the fluid would still pass through most of the length Yl of the wad that is heat treated in the first ~ 1 7~5~
Wo 9S/16065 PCr/US94/1399S
I~ortion 28. The propulsion pressure would have to be maintained on the end of the wad. With this variation in the position of the fourth portion, the length of the imper~orate first portion of the chamber would be the sum 5 of portions upstream and downstream of the perforate ~ourth portion. Jet 20 could be rp~pci~nl~d to provide a high steam flow at a low velocity, but it would be inconvenient to have to redesign and fabricate a new jet 20 for every new yarn or operating condition desired. It 10 is therefore preferred to design jet 20 for ~orwarding and rapidly heating the yarn, and providing a sQcond supply of low velocity fluid ~or bulk heating of the yarn to a uni~orm temperature. If a high flow of hot fluid i8 not required, the second fluid is not needed and the perforate 15 fourth portion in Fig 2 can be eliminated.
The yarn 40 is col 1 ected in the chamber 14 in loose folds ln imperforate portion 28. A given piece of yarn in the wad may remain in imperforate first portion 28 for a significant time period due to the slow advance of the wad 20 ana the length of imperforate first portion 28. The loosely folded yarn is heated by passing the heated first zmd second fluids through the loose folds to thereby heat set the ply-twist into the yarn. The loosely ~olded yarn i8 then cooled in imperforate second portion 30 to "lock 25 in" the ply-twist before the yarn is pulled ~rom the chamber .
In the case of Fig 1, the yarn is cooled by stopping the heating by venting the heated fluid at perforate third portion 34 and by making the length of 3 0 portion 30 long enough such that the yarn wad cools by contact with the walls of the elongated tube 12. The walls are exposed to ambient temperature conditions or this portlon of tube 12 may be perforate to expose the wad to a cool ~luid or a moving ambient fluid that increases 35 the heat transfer from tube 12.
In the case of Fig 2, the yarn is cooled by stopping the heating and passing a cool fluid through the yarn wad. The heating is stopped by venting the heated ~luid at peLrc~Lc-t.e portion 34. The cool fluid enters 2~ 77566 Wo 95116065 PCTIUS94/13995 chamber 14 through jet 22 and conical end 18 and passes through the loosely folded yarn in ~ ro,a~e portion 30.
The hot and cooler fluids meet in opposing flows and are vented from the loosely rolded yarn and the chamber in 5 perforate portion 34. The loosely folded yarn is unfolded into an eYtended length and passes through conical end 18 and passage 54 of cool jet 22, pulled by rolls 26. A
cooler fluid is directed at an angle to passage 54 through conduits 56 and 58 that are fed by cooler fluid source 60 10 through conduit 62 as in the jet device described in U.S.
Patent 3,525,134 to Coon. The cooler fluid flow opposes the forward motion of the yarn through the imper~orate portion 30, conic21 end 16, and passage 54. This acts to unfold the yarn as it is pulled from the ch2mber 14 by the rolls 26. The angle 64 made with the yarn 40 and the velocity of the fluid are such that the ~ in the yarn are not substantially disturbed or entangled in the multi ~ bundle. The cooler fluid flow passing through the wad rapidly cools the wad, the fluid pressure 20 reduces the requirement for a fricticnal length o~ wad to oppose the wad prop~ n by the hot rluid pressure and thereby stabillze the motion of the wad, and the cool fluid flow effectively unrolds the wad in a short space.
As a result, the length o~ the second portion of the 25 chamber can be m~n~m~79~1 by this cooling mode, thereby contributing to a compact assembly.
Referring to Fig 2, the flow Or the heated fluids through the loosely folded yarn in 1 -- rvLate portion 28 produces a prQpUl ~inrl ~resDuLe Pb on the end 66 of the 3 o loosely ~olded yarn. The rlow of the cooler fluid through the loosely folded yarn ~L.duces a retarding ~Lc6~uLe Pt on the end 68 of the loosely folded yarn in ~ roLate portion 30. Pb may be measured by sensor 67 that monitors the pLCD~ULC in chamber 14 adjacent the hot jet 20, and Pt 35 may be ~ d by sensor 69 that monitors the ~rcS~ULc in chamber 14 adjacent the cool jet 22. The ~ C~ULc Pv on the wad in perforate portion 34 is essentially atmospheric (Pv = 0 psig), since the fluids are vented in this portion. The fluid ~r'c~ .ULcS Pb and Pt in the chamber WO 95/16065 2 t ~ ~ 5 6 6 PCT/US94113995 ~
that act on the ends 66 and 68 of the wad 74 should be maintained at z low level, preferably less than 5 psig, so the wad is not compacted, resulting in sharp bends and kinks in the yarn. The loosely folded yarn sliding on the 5 inside surface oi~ the tube 12 produces a retarding force in the direction of arrow 70 proportional to the wall shear stress ~actor Tw, l ~ ~3~ ing the resistance of the fluid6 and yarn wad flowing in the tube 12. This reflects the dynamic ~riction of the yarn in the tube which depends lO on the surface finish inside tube 12 and the finish on the yarn. An ;~hAlAn-e between the propulsion pressure, wall friction, and retarding yLeS~-ULC: results in forward motion of the loosely ~o~ ded yarn through the chamber 14 in the direction of arrow 72. As the loQsely folded yarn wad 15 moves, yarn is added to the wad by yarn entering through jet 20 and yarn is removed from the wad by yarn being pulled away through; et 22 . The result is that the ends 66 and 68 o~ t~e moving loosely ~olded yarn wad remain at the same relative positions in chamber l~, and the length 2 o of the loosely folded section of yarn 74, shown in Fig 2 as a low density wad, remains a nearly constant length Yt.
In order to maintain the device operation in a stable state, the sensor 67, that senses chamber pressure Pb acting on the bottom of the wad, may be monitored by 25 the operator and the speed of nip roll motor 25 may be varied based on changes in the sensed pressure. It has been found that the plesDuL~ Pb is a good indicator of the length of the wa-d portion Yl for a given yarn. If Yl is kept constant, the pLesDuLe Pb remains constant and the 30 residence time for heat-LL-~a, L of the yarn in portion Yl remains constant. This results in a stable operating condition that produces uniformly heat-treated yarn. If Pb were to increase, it would indicate that the wad length increased (and rp~:idpnt e time increased), so the rolls 35 would be slowed to deposit less yarn in the chamber. If Pb were to decrease, it would indicate that the wad length decreased (and residence time decreased), so the rolls would be sped up to deposit more yarn in the chamber. It may be useful to automate the control of the nip roll Wo 95/16065 1 ~ 5 ~ ~ Pc~rluS94113995 speed by sending the output of the sensor 67 to controller 27 which can automatically vary the speed Or nip roll motor 25 in response to changes in the sensed chamber pressure Pb to maintain a preselected level of p~ ULe.
Rererring to Fig l, there is no pLeDDuLe Pt acting on the wad or yarn, so a s~f~ci~rt length or yarn wad is present in i-~yeLruLLLte second portion 30 to provide enough dynamic friction of the yarn in the tube to oppose the propulsion ~LaS-~ULe. A slight; -1 Anre as yarn i5 added and removed from the wad results in forward motion of the loosely rolded yarn through the chamber 14 in the direction of arrow 72. As the loosely folded yarn wad moves, yarn is added to the wad by yarn entering through jet 20 and is removed rrOm the wad as yarn is pulled away through conical end 18. The result is that the ends 66 and 68 of the moving loosely rolded yarn wad remain at the same relative positions in chamber 14, and the length of the loosely folded section of yarn 74 remains a nearly CUI~ GI~L length Yt.
2 0 Rererring to Fig 2, in operating the device, the residence time of the length Yt Or wad 74 is rl~t~rm; nPd for the desired heat-setting. Typically, times Or 90 or 120 seconds are used with the tl1luuy11~uL Or about 50 YPM
set by a yarn twister U~JD LL e:alU of the device . The tl1Luuy1~uL of the twister varies dep~n~9;n~ on the number of twis~s per inch put into the plied yarn. The hlgher twists per inch lower t_e yarn throughput and the yarn p~cks less densely in the chamber, resulting in a lower density wad. The r~ci~nre time aan be es~Ahl; Ch~d by csnc~ ring the wad density, the rlOw of hot fluid through the wad, the l,JLC~aULe Pb Or the first and second fluids on the wad, and the ~L~=SDULe Pt Or the cooler fluid on the wad. The ~eed speed and take away speed need to be selected and proportioned to the shrinkage Or the yarn.
The rirSt and second rluids are preferably steam that is prererably s~r~rh~Ated, and the cooIer fluid is preferably ezsDed air that may be heated to a temperature below the heat-set t~éLaLuLe o~ the yarn and the temperature of the hot ~luids. The initial wad length is det~rm;n~d by wo 9S/16065 2 l 7 7 5 ~ 6 PCTIUS94/1399S
the delay in taking away the yarn when the process is started up. The wad density and - v, L is also det~ n~9 by the opposing steam and air flows and the wall friction for a given yarn and twist level. The steam may typically be moving at about 16 ft/sec through the wad while the wad moves at about . 02 ft/sec. The method and apparatus are also compatible with higher speed twisters, such as an alternate twist ply machine using jets to twist the yarn at speeds of about 300 YPN. To achicve the same residence times at higher speeds, the chamber can be made longer or larger in ~;L~,ss-section i~ n~ A~y to ~c~ te more yarn.
The forces of the fluids flowing through the wad and the wall shear keep the wad in position as yarn is added and removed from the moving wad . Relatinn~h ~ rs that govern the steady state length of the moving wad during operation of the device are as follows.
The pLeS~UL ~ drop through the wad portion Y1 in imperforate first portion 28 is S:
S -- (uhvh/k) (~Le~uLa drop/length of wad) where uh is the viscosity of the hot fluid, vh is the mean velocity o~ the hot fluid through the wad based on the ~Las~>uL~ drop through wad portion Y1, and k is a factor related to the permeability of the wad, taken from Darcy's Law ~or ~Le~i~ULe and flow.
me pLes~uLa drop through the wad portion Y3 in imperforate second portion 30 is A:
A = (UCvc/k) (~L~=6~Lt: drop/length of wad) where UC is the viscosity o~ the cool fluid, and VC
is the mean velocity of the cool fluid through the wad based on the ~reD~uLe drop through wad portion Y3.
me friction of wad portion Yt along the chamber wall is F
F - 4Tw/D (shear stress/length o~ wad) ~5 where TW is the shear stress ~actor and D is the diameter of the chamber.
The total wad length is Yt Yt = Yl + Y2 + Y3 ~ WO 95/16065 2 1 7 7 ~ ~ 6 PCTIUS94/~3995 and for steady state conaitions:
YlS - Y3A 5 YtF (for Fig 2) Data was col 1 ectD~ for 24 test6 at stable operating conditions covering seven different nylon 6, 6 BCF yarns and two different heat-setting conditions producing various te ~LuLad looks using the device of Fig. 2. The following representative data are averages ror these tests:
Pb minus Pt = 15.44 inches of water ~ras~uLè
S ~ 4 . 74 (delta P in inches of water press . per inch of wad) A - 2 . 42 (delta P in inches Or water press. per inch of wad) F ~ l. 56 (stre~s in inches o~ water press .
per inch Or wad) Yl = 4 . 3 2 inches Y2 ~ 2 . 0 inches 2 0 Y3 = 2 . 6 6 inches Ytotal -- 8 . 98 inches D = l . 3 l inches Tw ~ 0 . 513 inches of water (dcrived from earlier experimental work) Pl - 2 . 5 psig P2 - lO. 0 psig Pv ~ 0 psig (ambient) Pb = 24 . 5 inches o~ water pressure In operating the device Or Fig l, it has been found that the cooling o~ the yarn does not always reS~uire forcing cool rluid through the wad of yarn. In some cases, the yarn may be cooled s~ff~ri~tly by passing the yarn through the unheated second portion 30 of the chamber 14 beyond the peLr-,Lal,e third portion 34 where the heated rluid is vented. When this second portion is long enough, the wad will spend enough ti~e in this second portion 80 the yarn will cool below the heat-treatment tL.~.~éLaLuLa.
This second portion may be i. ~eLruLa-e as shown in Fig l, wo 95/16065 2 1 7 7 5 ~ 6 PCTiU~94/13995 or it may be pelr.,Lc.te to 2110w passage of a cooling fluid, for instance in a direction ~ Vt:L~.e to the wad 74 and chamber 14, to speed up the cooling. When the total wad length Yt is long enough, the friction o~ the 5 wad in the chamber will be sl1ff~ nt to balzmce the ~Le:S::iUL~ Pb acting to propel the yarll wad. With this controlled propulsion, a constant, steady state, length of yarn wad result6. In this situation, the above-aescribed steady state formula becomes:
YlS 2 YtF, since there i8 no oppos~nq p~s--u~e: acting on wad lQngth Y3 .
In this case, the end of the wad 68 may be located adjacent the conical end 18, but preferably the wad does 15 not contact the end 18. The small diameter of the conical end helps stop any clumps of yarn from exiting the chamber and entering nip rolls 26. Alternatively, the length of the second portion of the chamber 14 may be shortened, the angle of the cone may be reduced to about 10-20 degrees 20 included angle, and the wad allowed to contact the tapering walls of the conical end 18. This contact with the tapering walls provides a gentle resistance to yLt:S~ULe: Pb without creating problems of wad clumping and j amming that may occur with a stéeper cone angle . The 25 longer length o~ the ~h~ L angle cone end also provides more space for unfolding than the steeper angle cone. Three means have been tl~cl~sec~ for resisting Pb to stabilize wad - ~ L: l~ providing a long chamber length to develop s~ff~ci~nt frictional resistance with a long 3 0 wad length; 2 ) providing 2 shallow angle cone end to retard wad - ~ L without clumping and jamming: and 3) providing a retarding plessuL~ Pt on the end of the wad that may also serve to rapidly cool the wad. The third means is preferred to provide the most compact and easily 35 controlled arrangement for the device.
The device of this invention can be operated over a variety of conditions to produce a variety of results.
For instance, the device can be operated as described above, where an elongated portion of loosely gathered yarn Wo 95/16065 2 t 7 ~ ~ 6 ~ PCT~'S94/13ss5 is allowed to accumulate in the chamber 2nd dwell there for an ~ ~t~n~'Qd time to produce a yarn that is bulked and fully heat-set. In another case, le6s yarn can be accumulated for a shorter time so that _ lete heat-setting does not occur. In still another case, only a small portion of yarn is; cc~ A~ted ~or only a few - seconds so that no appreciable heat-setting occurs, but the yarn product is still fully bulked in the device under no tension. Operation of the device in order to only bulk the yarn may be useful if it is desired to s~hsecluPntly heat-set the yarn in a subsequent step, such as with the Suessen device referred to above. It is believed that one problem with the Suessen device is that it cannot remove tension effects caused by gravity and friction acting on the yarn loops hun~ on its forwarding ~- Ani~, so non-uni~ormities in bulk may result. Thus, separately bulking the yarn under zero tension before subsequent heat-setting has been found to be ~ ~-n~ ciA7 .
Tests have shown that nylon BCF yarn which was first bulked in the device of this invention and then passed through the Suessen device had better bulk uniformity than nylon BCF yarn which was both bulked and heat-set in the Suessen device. This ~ d uniformity was evident when the nylon BCF yarns were made into cut pile saxony carpet samples. A repetitive pattern called "chevrons" was a}~sent in the carpet sample having yarns which were separately bulked in accordance with this invention. However, these chevrons were present in the carpet sample having yarns bulked on the Suessen.
As previously mentioned, the device has a high degree of flexibility in operation to produce a variety of products. In turn, these yarns may be used to prepare carpets having various t~:,.LuL~:s . It is also re~o~n ~ 7~C7.
that varying t~e twist level in the yarn and the composition of the synthetic 1'-1~ t,. of the yarn produce further product variations.
In general, the device has been found to operate well and make useful nylon 6, 6 BCF yarn products when operated over a range of t~ CLLULe:S from about 160 to W0 95/16065 2 1 ~ 7 5 6 $ PCTIU594/13995 ~
210C, A yllrn entrance speed o~ about 50 yds/min, And ~
range o~ heat-treatment r~ci~ nre times from ~Ibout 60 to 180 seconds during which time the yarn is between the el1~La11ce and exit of the device (essentially always in the 5 loosely folded condition). It is believed the device would also operate well at speeds up to about 500 YE~. It is believed important to good heat-treatment that the yarn be held at a t~l~LaLure below its melt polnt for an extended period of time to insure all ~1 in the 10 yarn bundle reach the same tc~ La~uLc:; this results ln highly unlform heat-treating of the yarn. Carpets composed of nylon yarn samples made outslde the lower end of the ranges stated above showed poorer texture retention, tuft deflnition, and texture.
It i6 also recoqn~ 7"~ that a plurality of ply-twisted ends may be passed through the devioe simultAneo~1c1 y without p~ n~ntly ent~nq1; nq the yarn Qnds. The mass flow rates and passage diameters would have to be adjusted to A~ te the greater total 20 denier of yarn. In order to aid in separation of the plied yarn ends after exiting the elongated tube 12 and before r~A~h1n~ the means to remove the yarn, the combined yarn ends can be passed through a known tensioning device, such as a ladder type t C~ncion~ and passed over a long 25 ~n~ l ~ ,L ~ed span under tension as shown in Fig. l . The individual plied yarn ends could then be separately wound on bobbins for furtber proc~ ing. Such a winder can be the means for removing the yarn. Six ends of yarn were ~Lvcessed through the device of Fig l with the addition of 30 a second heated fluid through a perforate fourth portion, such a6 portion 32 in Fig 2.
Although the device has been described as belng oriented vertically with the yarn entering the lower end o~ the device, it is believed that the device orientation 3 5 is not critical and the device could be oriented horizontally or at an angle to horizontal, or the device could be operat~d with the yarn entering the upper end.
various known methods for initiating ~ormation of the wad ~ WO95/16065 2 1 77~ PCr/Uss4113995 can be used and the means to ~eed yarn and remove yarn controlled to then position the wad ends in the chamber.
The present invention is further illustrated in the following Examples, but these r ~ lPC should not be 5 concidPrpd as limiting the scope o~ the invention.
T~8TING MET~OD8 The following Testing Methods were used to measure various yarn and carpet sample properties, as further l0 described in the below r lPq.
C~rP~t W~r Wear tests which closely correlate to floor tra~ficking were conducted in a Vetterman drum test 15 apparatus, Type RSG manu~actured by S~-hoPnhPry ~ Co.
(Baumber, Fed. Rep. o~ Germany). As spP~if;ed, the drum is lined with carpet samples into which i5 placed a 16 pound steel ball having ~ourteen tl4) rubber buffers which rolls randomly inside the rotating drum. A circular brush 2 o within the drum is in light contact with the carpet surface and picks up loose pile i~ibers which are cont;nl10ucly removed by suction. After 5,000 cycles, the samples are removed and inspected to evaluate texture retention. Texture retention or "newness retention" is 25 reported on a scale of 1-5 with a rating o~ 5 corrPspnn~l;n~ to an untested control s2mple, 4 corresponding to a lightly worn sample, 3 to a moderately worn sample. A rating of 2 ~ OLLe:~ull~S to unacceptable wear, and l corresponds to an c:x~ ~ -1 y matted sample.
C~rl~et Bulk Carpet bulk was measured as the __~sYed pile height in inches of a carpet sample that is loaded with a ~L_S~uLe: 0~ 1 lb./in2 (703 kg/m2). The carpet sample is 35 placed on a platform which is attached to a vibrator. The sample is vibrated lightly for 5 seconds prior to measuring the pile height using a thickness gauge which is also attached to the vibrating platform. The vibration allows the foot o~ the th;c~nPCc gauge to settle into the WO95/16065 2 l 7~6 PCr/US94/13995 ~
surface of the carpet. Carpets with high bulk values have high readings of REU.
8hri~-kA~ Forco The shrinkage force o~ the yarn samples was measured on a thermal analyzer made by the Kanebo Company.
A closed loop of sample yarn W7S placed between two spaced pins in an oven. All of the slack was removed from the loop and a load cell was attached to one o~ the pins to record shrinkage forces in grams as the sample was slowly heated in an oven over a period of time. A plot of temperature and tension is recorded for each sample as it shrinks .
EXa~Pl,Es A ply-twisted yarn, comprising a pair of nylon 6,6 bulked continuous filament (BCF) yarns, Type ~150-696AS, available from the DuPont Company, having a denier of 1150 each, and ply-twisted at a twist level of 3.75 turns per inch, was processed through the device of Fig 2 controlled by the operator at a variety Or operating conditions. The treated ply-twisted yarns were tufted into a backing material to form cut-pile carpet samples each having a weight o~ 32 oz/yd2 and 2 pile height of 5/8 inches. As illustrated in Fig 4, four cut pile carpet samples were compared in a side-by-side comparison under the same viewing light conditions and given the following ratings:
C-l9 - a low to no t~ uL-~d appearance;
C-24 - a low textured appearance;
C-35 - a medium textured appearance; and C-39 - a high textured appearance providing a highly variegated effect.
The following Table I summarizes the different operating conditions to produce the yarns for the four above-described carpet samples using a cylindrical chamber of about 1.31" ~ r and about 37" long, where the imperforate first portion was about 21" long, or about 57%
of the length of the chamber. The perforate third portion of the chamber was about 2 " long or about 5% of the length 21 775~6 Wo 95/16065 PCT/US94/13995 of the chamber and the perforate ~ourth portion was about 3 " long .
TABLE I
S
C-l9 C-2 4 C-3 5 C--3 9 ~ .
T~ ~LUL~ T4, (C) 188.6 196.3 200.3 204.0 lO Yarn Res . Time, 92 . 6 119 . 5 95 . 5 123 . 5 (seconds ~or Yt) P1 ( ~- LL llnce j et press 2 . 5 2 . 5 2 . 5 2 . 5 in psig) do (entrance jet size 40 (1) 40 (1) 80 (1) 80 (2) in mils) P2 (exit jet press 10 10 10 10 2 0 in psig) (l) only one steam port on entrance jet (2 ) two opposed steam ports on entrance j et 25 Com~r~tive ~3~m~1e~
In comparative tests, untreated Type 1150-696AS BCF
nylon yarns, as described above, were passed through a Suessen heat-setting device under a ,~ 'e~ setting ~or the sample yarn of about 40 seconds r~ci~l~nce time at 30 195C hot air temperature under ambient ~LaS~ULe:. In another instance, the untreated Type 1150-696AS BCF nylon yarns were passed through a Superba heat-setting device at a ~ 7 setting for the sample yarn o~ about 40 - seconds residence time at 132C steam t~.~.~eLllLULt: under 35 about 15 psig ~ s,,u,e. The yarns were respectively tufted into backing materials to ~orm two ai~ferent cut-pile carpet samples each having a weight of 32 oz/sq.yd.
and a pile height of 5/8 inohes. The carpet samples had a e~ pearance WO95/16065 21 77~G PCT/US94/13995 ~
The following Table II provides some peL rVLlUanCe data for the above-descrlbed carpet samples.
RT.~ II
(Suessen) (Superba) C-l9 C-24 C-35 C-39 Control Control lO Texture 2.9 2.7 2.7 2.2 3.1 2.5 Retention Reu Bulk 0.499 0.478 0.439 0.464 0.472 0.461 ( l lb ) As shown in the above Tables, Sample C-l9, having a low to no textured appearance, contained yarns processed through the device of Fig 2 with the minimum steam ~low rate through the forwarding; et that would still tension the U~DLL~alU yarn enough to reliably strip the yarn off the feed rolls. This rlow rate was achieved using a single 40 mil jet conduit. The texturing effect of the device seemF: to be most 3ensitive to the steam flow rate through the forwarding jet; a higher flow rate of steam spreads the plied yarn apart and bends it more sharply as it is folded in the chamber.
Sample C-24, having a low textured appearance, was slightly more textured than C-l9, and this was obtained by increasing the t~ _ atULe: and time that the loosely folded yarn was exposed to the steam in the chamber.
Sample C-35, having a medium textured appearance, was made by increasing the flow rate by using a larger conduit in the jet: the effect of the temperature and time changes with this sample were considered insignificant.
Sample C-39, having a highly textured appearance, was made by further increases in the flow rate by providing another conduit in the jet; the effect of the temperature and time changes for this sample were cnn~ red insignificant.

4 0 The yarn samples made in the device of this invention that were tufted into carpet did not show any characteristics of poor bulk uniformity, such as W0 95/16065 2 1 7 7 ~ ~ ~ PCT/US94/13995 "chevrons", in the tufted cut pile carpets. The yarn samples made in the device o~ this invention that were al60 tu~ted into carpet samples had better stain resistance (characterized by a slow dyeing rate) when 5 compared with the comparative yarn samples heat-treated in the Superba device. The dyeing rate o~ the yarn samples - made in the device of thi6 invention was similar to the dyeing rate of the comparative yarns heat-treated in the Sues~en device.
Another yarn characteristic indicative of molecular micro-,,L,~ LuLc WaS measured, the Kanebo chr;nk~e~ to distinguish the above-described inventive yarn samples from the comparative yarn samples.
A characteristic plot o~ temperature and tension is recorded for each yarn sample as it shrinks. Fig 5 shows a plot Or a single yarn type treated with the device o~
the invention under two different operating conditions compared to treating in the Suessen and Superba devices and to no treating. Samples C-24 and C-l9, which typi~y products o~ the invention, are shown as curves 88 and 89 respectively. The control l sample treated on the Suessen device is shown as curve 90, and the control 2 sample treated on the Superba device is shown as curvc 92. The non-heat-treated sample is shown as curve 94.
It is believed that the shape and position of the shrinkage data curves of the yarns o~ this invention relative to the comparative yarn samples re~lect a characteristically dirferent molecular micro-structure o~
the yarns Or this invention. There~ore, it is believed 3 o that the nylon BCF products treated in the device of Fig 2 are distinctly different and novel compared to the same nylon BCF yarn treated in known conventional devices or not treated at all. It is believed that the differences between the novel nylon heat-treated products and conventional nylon heat-treated products may be related to the novel process steps Or the invention where the yarn is treated in the rorm Or a wad, and in some part to the use o~ s~lr~rhP~ted 6team at low ~Le~-lLt: as the pre~erred L. ~:~li L rluid in the device.

-WO95/16065 ;~ 6i PCT/US94113995 More p~rticularly, these yarn products may be made in accordance with the following method:
a) heating the yarn with sl~rPrho~ted steam;
b) forwarding the yarn with the superheated steam 5 into an elongated chamber, said chamber having an imperf orate f irst portion and a second portion, such that a loosely foldea wad of yarn is formed within the imperforate first portion of said chamber and contained within the second portion;
lo c) forcing the sl~r~-h~ted steam through the wad in the first portion of the chamber;
d) venting the sllrorhP~ted steam through a perforate third portion of said chamber int~ te the f irst and second portions;
e) cooling the yarn within the second portion of said chamber; and ~) removing the yarn from the chamher.
Such products are also po~ hle when a cool i~luid jet is added to the process and/or a supply of second s~rPrh~nted 20 steam is ndded as ~ ~ scl~c~e~ above.

Claims (21)

CLAIMS:

1. A method for treating a multifilament yarn, comprising the steps of:
a) heating the untreated yarn with a heated fluid;
b) forwarding the yarn with the heated fluid into-an elongated chamber, said chamber having an imperforate first portion and a second portion, such that a loosely folded wad of yarn is formed within the imperforate first portion of said chamber and contained within the second portion;
c) forcing the heated fluid through the wad in the first portion of the chamber;
d) venting the heated fluid through a perforate third portion of said chamber intermediate the first and second portions;
e) cooling the yarn within the second portion of said chamber; and f) removing the treated yarn from the chamber.

2. The method of claim 1, wherein the heated fluid is superheated steam.

3. A method for treating a multifilament yarn, comprising the steps of:
a) heating the yarn with a heated fluid;
b) forwarding the yarn with the heated fluid into an elongated chamber, said chamber having imperforate first and second portions and a perforate third portion intermediate the first and second portions, such that a loosely folded wad of yarn is formed within the imperforate first portion of said chamber and contained within the second portion;
c) forcing the heated fluid through the wad in the first portion of the chamber;
d) forcing a cool fluid through the loosely folded wad of yarn within the imperforate second portion of said chamber in a direction opposing the flow of the heated fluid, such that the heated and cool fluids meet in opposing flows within the perforate third portion of said chamber;
e) venting the heated and cool fluids through the perforate third portion of said chamber; and f) removing the yarn from the chamber.

4. A method for treating a multifilament yarn, comprising the steps of:
a) heating the yarn with a first heated fluid;
b) forwarding the yarn with the first heated fluid into an elongated chamber, said chamber having imperforate first and second portions and a perforate third portion, such that a loosely folded wad of yarn is formed within the imperforate first portion of said chamber;
c) supplying a second heated fluid into the imperforate first portion of said chamber and forcing the first and second heated fluids through the loosely folded wad of yarn within the imperforate first portion of said chamber;
d) forcing a cool fluid through the loosely folded wad of yarn within the imperforate second portion of said chamber in a direction opposing the flow of the heated fluids, such that the heated and cool fluids meet in opposing flows within the perforate third portion of said chamber;
e) venting the heated and cool fluids through the perforate third portion of said chamber; and f) removing the yarn from the chamber.

5. A method for treating a multifilament yarn, comprising the steps of:
a) heating the yarn with a first heated fluid;
b) forwarding the yarn with the first heated fluid into an elongated chamber, said chamber having an imperforate first portion, a second portion, and a perforate third portion intermediate the first and second portions, such that a loosely folded wad of yarn is formed within the imperforate first portion of said chamber and is contained within the second portion;

c) supplying a second heated fluid into the imperforate first portion of said chamber and forcing the first and second heated fluids through the loosely folded wad of yarn within the imperforate first portion of said chamber;
d) venting the heated fluids through the perforate third portion of said chamber;
e) cooling the yarn within the second portion of said chamber; and f) removing the yarn from the chamber.

6. The method of claim 4, wherein:
a) the first heated fluid is superheated steam having a temperature greater than 150°C at a pressure less than 5 psig entering the chamber;
b) the second heated fluid is superheated steam having a temperature greater than the temperature of the first heated fluid at a pressure less than 5 psig entering the chamber; and c) the cool fluid is air having a temperature less than the first heated fluid at a pressure entering the chamber which is less than the heated fluids.

7. The method of claim 4, wherein the step of forwarding the yarn with the first heated fluid comprises forwarding the yarn through a fluid jet at a first heated fluid pressure to the jet between 1.5 and 10 psig; and the step of forcing a cool fluid through the wad of yarn comprises passing the cool fluid through a jet directed at the wad, at a cool fluid pressure to the jet between 1.5 and 10 psig.

8. The method of claim 4, further comprising the step of withdrawing the vented heated and cool fluids away from the exterior of said chamber.

9. The method of claim 4, wherein the multifilament yarn is a ply-twisted, multifilament yarn comprising at least two component yarns.

10. The method of claim 9, further comprising the step of passing the ply-twisted yarn through a heat-setting device, wherein the twist is heat-set, subsequent to removing the yarn from the chamber.

11. The method of claim 4, wherein the yarn is selected from the group consisting of nylon 6,6 and nylon 6 yarns.

12. The method of claim 11, wherein the yarn is selected from the group consisting of bulked continuous filament yarn and staple yarn.

13. A tubular apparatus for heat-treating yarn, comprising:
a) an elongated chamber having a yarn entrance end and an opposing yarn exit end, said chamber having a diameter substantially larger than the diameter of the yarn to be treated and further comprising:
i) an imperforate first portion adjacent to the yarn entrance end for collecting loosely gathered folds of yarn and heating the yarn, the length of the imperforate first portion comprising at least 40% of the length of the chamber;
ii) a second portion adjacent to the yarn exit end for containing loosely gathered folds of yarn and cooling the yarn; and iii) a perforate third portion intermediate the imperforate first portion and the second portion for passing fluid out of the chamber through the loosely gathered folds of yarn; and b) a fluid jet attached to the yarn entrance end of the chamber for forwarding the yarn in an extended length into the chamber and introducing fluid into the chamber.

14. The tubular apparatus of claim 13, wherein the second portion is imperforate, and the apparatus further comprises:
c) a fluid jet attached to the yarn exit end of the chamber for passing the yarn in an extended length out of the chamber and introducing fluid into the imperforate second portion of the chamber in a direction opposed to the passing of the yarn.

15. The apparatus of claim 14, further comprising a perforate fourth portion adjacent to the yarn entrance end of the chamber for introducing additional fluid into the chamber.

16. The apparatus of claim 13, further comprising:
c) means to sense the fluid pressure in the chamber due to the fluid introduced at the yarn entrance end; and d) means to feed yarn into the chamber including means to vary the feeding based on the sensed pressure.

17. The apparatus of claim 16, further comprising:
e) means to sense the temperature of the wad in the first portion of the chamber; and f) a source of fluid and means to supply heat to the fluid introduced into the chamber including means to vary the heat supplied based on the sensed temperature.

18. The apparatus of claim 16, further comprising means to remove yarn from the chamber.

19. The apparatus of claim 13, wherein each end of the chamber is conical-shaped.

20. The apparatus of claim 17, further comprising:
g) control means to vary the feed means in response to the sensed pressure in the chamber and to vary the heat supplied in response to the sensed temperature of the wad.

21. A nylon bulked continuous filament yarn produced in accordance with the method of claim 2.