US3176373A - Methods of texturizing filaments - Google Patents

Description

April 6, 1965 E, A. TAYLOR, JR 3,176,373

METHODS OF TEXTURIZING FILAMENTS Filed Dec. 12, 1960 3 Sheets-Sheet 1 INVENTOR. ERNEST A TA YLOR,JR

FIG. 3 BY/4%?! ATTORNEY E. A. TAYLOR, JR

METHODS OF TEXTURIZING FILAMENTS April 6, 1965 3 Sheets-Sheet 2 Filed Dec. 12, 1960 FIG. 4.

0? xe v7 2 5 o" .020" .040" .060" .080" .noo" J20" J40" CLEARANCE BETWEEN ORIFICE AND ROLL INVENTOR. ERNEST A. TA YLOR,JR wf ATTORNEY United States Patent 0 3,176,373 METHODS OF TEXTURlZlNG FlLAPvlENTrl Ernest A. Taylor, .lr., Decatur, Ala, assignor, by mesne assignments, to Monsanto (Zompany, a corporation of Delaware Filed Dec. 12, 195i), Ser. No. 75,299 6 Claims. (Cl. 28-72) This invention relates to methods of texturizing filaments and more particularly to methods of dillerentially texturizing synthetic textile filaments or fibers.

It is a well known fact that it is necessary to textnrize or crimp man-made fibers which are to be cut into staple. The reason for this is that it is necessary to provide some fiber characteristics which will resist longitudinal movement of one fiber relative to another. Without this characteristic the staple fibers would slide too easily along each other in the assembled yarn, thereby resulting in a yarn of very little tensile strength. Natural fibers such as wool have an inherent crimp or curl which provides a good frictional engagement between adjacent fibers. However, man-made fibers, which are inherently straight, must be treated in some way to impart good frictional characteristics. It is also necessary to treat continuons-filament, man-made fibers to give them better covering characteristics, greater stretchability and a better hand.

One method of so treating synthetic textile fibers is to texturize or crimp the fiber. The crimping is usually accomplished by passing a heated tow of filaments between a pair of gears, the teeth of the gears imparting a wavy configuration to the thermoplastic filaments. This arrangement has several disadvantages. One of these disadvantages is that, due to the physical limitations on gear teeth sizes, it is not possible to obtain a crimp of very small size. The same is true where smooth crimping rolls are used. Another disadvantage is that a pair of given crimping gears cannot be used to obtain a crimp of various sizes. By crimp size, we mean generally the amplitude and length of the wavy configuration imparted to the filaments by the crimping operation.

A further disadvantage of conventional gear crimping operations is that these operations cannot produce a tow in which the filaments are completely looped, i.e., where the slack filament configuration defines a series of loops rather than a wave configuration.

Other types of crimping or texturizing operations involve pulling the yarn across a knife edge or twisting the yarn and then heat setting it. The disadvantage of these types of texturizing operations is that the apparatus has limited life or is not conducive to high speed operation. In crimping operations where rolls feed the yarn into a hot stufiing box the high heat duration is likely to result in poor dye uniformity.

With these problems in mind, one of the objects of this invention is to provide a novel and improved method for treating a filament.

Another object of this invention is to provide a novel method of impartin a crimp or curl to a filament.

A f rther object of this invention is to provide a method for texturizing a thermoplastic filament wherein the amount of crimp or curl imparted to the filament can be later varied by heat treatment of the filament.

Still another object of this invention is to provide a method of texturizing a filament by differentially heat ing the filament.

Yet another object of this invention is to provide a method of texturizing a filament by heating one side of the filament while cooling the other side thereof.

A method illustrating one embodiment of the invention comprises passing a thermoplastic fiber filament under tension through a zone where one side of the filament ice is cooled while the other side thereof is heated to a temperature sufficient to soften or plasticize the heated side. The heated side of the filament will be stress-relieved while it is in the heated condition. The cooled side of the filament, however, does not attain the temperature necessary to accomplish this. The frequency and amplitude of the resulting crimp or curl is a function of the temperature that the heated part of the yarn attains, the temperature of the cool side of the yarn, and the ten sion on the yarn.

When tension is removed from the fiber filament the stress-relieved side does not contract, while the other side, which has retained its elasticity, does contract. This pulls the filament into a series of tight coils, the diameter of which is determined by the degree of stress relief in the heated side of the filament. This series of coils actually forms a helix which coils first one way and then the other, since the filament does not actually twist longitudinally.

in a method illustrating the principles of the invention in greater particularity, a thermoplastic filament under tenison is wrapped round and advanced by a rotating roll which is relatively cool. A narrow stream of heated gas is directed from a nozzle onto the filament to heat the exposed side thereof to a temperature suificient to soften that side of the fiber. The cool roll in contact with one side of the fila ient serves as a heat sink to prevent a temperature rise in this side, while the temperature of the exposed side is elevated, the actual temperature being determined by the temperature of the gas and speed of the filament. This stress-relieves one side of the filament while leaving the other side unchanged. Thus, when tension is removed from the filament it curls up into a series of tight coils which define a helical configuration. NaturaLy, when a yarn having several individual filaments is treated by this process the yarn is bulked considerably.

Other objects and advantages of the invention will become apparent when the following detailed description is read in conjunction with the appended drawing, in which:

FIGURE 1 is a side view of apparatus for performing a texturizing operation in accordance with the principles of the invention;

FZGURE 2 is an enlarged view showing a nozzle used to direct heated air onto a filament to be texturized;

FXGURE 3 is an end view of the air nozzle of FIGURE 2 showing the flow paths of the heated gas;

FlGURE 4 is an enlarged cross-sectional view of a heat-sink roll over which the yarn is passed during the operation;

FIGURE 5 is a graph showing yarn bulkiness in terms of the spacing of the nozzle relative to the heat-sink roll carrying the yarn; and

FIGURES 644 are graphs showing results of runs made in accordance with the principles of the invention.

Referring now in detail to the drawings, FIGURE 1 shows apparatus for carrying out the invention. A thermoplastic yarn 11 consisting of one or more individual filaments is advanced from a supply bobbin 12 past a tensioning device 14 of a conventional type to a heatsink roll 17 which is driven in a well known manner. The yarn is wrapped one turn around the roll 17 and then advanced to a driven takeup roll 18 of a conventional type.

A nozzle 21 positioned adjacent to the roll 17 directs a stream of heated gas from a source 22 onto the yarn 11. The nozzle 21 is positioned very close to the yarn ll so that the exposed sides of the individual filaments are heated to or near the softening or melting point of the thermoplastic material so that these exposed sides are relieved of inherent stress. Since the yarn 11 is under tension on the roll 17, it will be flattened and spread so that the individual filaments are both exposed to the heated gas and in contact with the heat-sink roll 17. The occasional loss of contact of a filament with the roll due to crossed filaments does not, seemingly detract from,

Texturizing Filaments, may be made of stainless steel 7 and is providedwith a rectangular opening 23 through which heated air or other gas is directed onto the yarn.

The nozzle is positioned so that the long axis of the rectangular opening 23 is'transverse or perpendicular to the path of travel of the yarn. A typicalnozzle may'have an outside diameter of A inch, a rectangular orifice 0.015" x 0.125, and be spaced 0.008" from the surface of the heat-sink roll 17. V p

FIGURE 3 shows the flow pattern of heated air leaving the opening or orifice 22 and passing between the end of the nozzle and the roll 17. From this it can be seen that the major portion of the heated air flows in a direction parallel to the yarn path. The flow pattern is determined by both the clearance between the end of the orifice and the periphery of the roll, and by the shape and position of the exit orifice. This flow pattern does not disturb the positioning of the individual filaments of the yarn as a transverse air current would. V

The reason for'this unexpected air flow pattern is not fully understood, but it is believed that at points B (FIG;

the orifice 22, while, beyond points A, well defined.

streams of airare flowing away from-the orifice.

The roll 17, vwhich is shown in detail in FIGURE 4, is secured to a driving shaft 26 'and'positioned adjacent to a manifold 27 which has an air intake opening 28 and an air exhaust opening 29. The roll 17 is provided It has been demon-,-

here refers to the difference in length of the treated fila ment between a fully extended state and a relaxed state) obtained by various nozzle spacings. The yarn used was 115 denier, 34 filament nylon which was moved past the nozzle described above at a rate of 150 feet per minute.

, The air pressure used was 25 psi. and the air temperature was 920 F. with a draw 'ratioof 2.42. 'From the graph 'it can be seen that, with this particular set of conditions,

i the best bulking was obtained at a nozzle spacing of about 0.008 Under these conditions, including variations in nozzle size and orifice size andspacing, other nozzle spacings may be more desirable.

Depending upon roll size, speed, material, and the quantity of heated gas impinging upon its surface, it may not benecessary that the roll 17 actually be cooled.

Excellent bulking has been obtained'when the roll 17 was kept barely warm to the touch-apparently about 90 F. The exact upper} limit of draw roll temperature is not known, since it has not been possible to actually measure the temperature of the rotating roll. However, if the 'surfaceof the roll becomes too warm there is a pronounced decrease in the degree of texturizing or bulking.

- The roll temperature should bekept low enough that little .or no stress-relief occurs in the cooler side of the yarn.

Only a small part of the heat expended goes into the roll 17, most of it remaining in. the gas exhausted from the nozzle. The gas, since it does not cling to the roll and the yarn as a wetting liquid would, adequately heats the exposed side of the yarn without :overly heating the roll or the filaments in the yarn. A liquid heating medium would probably surround and adhere to the filaments of the yarn to heat substantially all of each filament. This would'not achieve the desired result, which is basedon heating one side of the filament while main- 1 taining the other side at a relatively low temperature.

with a face plate32 and a plurality of intake cooling However, a non-wetting liquid such as molten solder might be used for heating the exposed side of the yarn.

The periphery. of the roll 17 would extend intoa pool only the exposed side of the yarn.

The air temperature andpre'ssure and the yarn speed are variableswhich are dependent upon each other, given a nozzle spacing and size. FIGURES 6-14 serve as examples to show bulking or texturizingobtained when haust opening in the manifold27. This cools the roll 17 so that it' serves as a heat sink or heat absorber to keep one side of each of the individual filaments of the yarn 11 relatively cool as the other side isheated.

Factors which affect the yarn bulking ortexturizing operations are air temperature, spacing of the nozzle from the roll, air supply pressure, yarn speed, yarn tension, and draw roll temperature. The amount of heat that must be applied to the exposed side of the fiber will 7 vary in accordance with the softening or. melting point of the fiber. Thus, a fiber having a relatively low .melt

ing point will not require as much heat for bulking as will a high melting point fiber. Since it is very difficult to actually determine the yarn temperature, the process is best carried out by controlling the air'press'ur'e and temperature to give the desired result on the particular.

FIGURE 5 shows the results of runs made to determine; 7

the perecent of yarn bulking (the term bulking as used these three factors are varied. These runs were made using the above-described nozzle spaced 0.008" from the roll 17,'the yarn being denier, 34 filament nylon. Of course, the yarn ca n be run at lower speeds than shown in ,FIGS.6- 14. by using lower air temperatures, or at higher speeds by using higher air temperatures. Also, monofilaments can be treated with equal success.

The yarn treated by this process can be used in any application where bulkexi or texturized yarn is desired. In addition, this yarn can be used to make nonwovens of widely varying characteristics.

' These unique nonwovens are formed by winding the bulked or texturized'yarn, under tension, onto a takeup roll of a desirable size, as shown in FIGURE 1. After a sufiicient layer of yarn is wound onto the takeup roll, the roll is stopped and the yarn layer is cut longitudinally and removed from the roll. This removes the tension from' the yarn so that it may contract freely. As the bulked filaments contract (i.e., assume their texturized configuration) the filaments form coils and loops that interlock with'the coils of adjacent filaments, thereby forming a mat or batt of intimately associated, interlocked filaments.

The size, thickness and textureof the batt formed by been texturized with equal success.

this method depends upon the degree of texturizing or bulking of the yarn. For example, a layer of highly bulked yarn was wound under tension onto a bobbin having a circumference of approximately inches, the yarn being traversed onto the bobbin at a low helix angle. When the yarn layer was cut longitudnally it contracted to a width of about 2 inches (from the original 10 inches). The edges and sides of the batt were smooth and rounded and no loose ends of the severed filaments were visible. In fact, it was impossible to find the loose ends merely by visual inspection. The individual filaments in this batt were helical in configuration, with a helix diameter of about 0.05 inch. A 1 length of yarn, when relaxed, would have 7-8 loops. A length of yarn extending, in its relaxed state, a distance of 1" might contain 60 to 80 loops. The longitudinal length of the yarn layer changed very little, while the circumferential length decreased approximately 80% and the thickness of the batt increased 10 to 12 times.

These nonwoven batts or layers can be formed by winding the bulked yarn onto rolls, drums or forms at any desirable shape or by lacing the yarn in a fiat plane under tension until a suflicient thickness has been achieved. Release of tension on the layer will then allow the yarn filaments to contract to form a tightly interlocked, l ighly lofted, nonwoven batt. The resilience of the batt due to the coil filaments permits it to be crushed and to then recover its thickness when the pressure is removed. The filaments can further be locked together by treating the batt with steam or heated air, while a treatment of latex or some type of resinous binder can make a permanent structure.

The process of the present invention can thus be used to form non-Woven batts as well as the texturized or bulk yarn. The bulking operation works as well on multifilament yarn as on monofilament. Either monofilament or multifilarnent yarn can be used to form the nonwoven batts. Also, the process is successful on filaments of widely different cross sectional configurations. For example, round, triangular and Y-shaped filaments have The denier of the filaments is not important except that with smaller denier, smaller helixes can be formed.

The fact that one side of the filament is heated to or above its softening point while the other side is cooled results in a texturizing or bulking of the yarn, the degree or amount of texturizing being dependent upon the yarn temperature differential under a given yarn tension. The relatively cool roll 17 in contact with the yarn filament-ts serves as a heat sink to prevent an undesired temperature rise in one side of the filaments. Thus, one side of each filament is cool relative to the other side.

The fact that heat is applied to the yarn at one point, rather than along a length of yarn, insures a superior result. This is because one side of the filament is heated to a high degree while the other side is kept relatively cool. If the yarn is heated along a length it is likely that, because of a twisting of the yarn under tension, portions of i the yarn will be heated to equal degrees on both sidesresulting in no texturizing. It is well known that a yarn under tension may twist or turn slightly as it is advanced. If this twist occurs in the span or length of yarn which is being heated (as where the yarn passes over a heated moving belt), it may well result that both sides of the filament are heated to equal temperaturesone side being heated before the twist and the other side after the twist. By heating the yarn at a single point, this disadvantage is overcome.

It is to be understood that the process-disclosed herein may be modified or that other embodiments may be contemplated without departing from the spirit and scope of the invention.

What is claimed is:

1. The method of treating a synthetic textile filament, comprising passing the filament through a treating zone under tension, and simultaneously heating and cooling opposite sides of the filament in said zone, said heating being done at substantially a point location in said zone, said heating being sufficient to stress-relieve the heated side of the filament.

2. The method of treating a synthetic textile filament, comp-rising placing said filament under tension, and heating one side of the filament to near its melting point while maintaining the other side of the filament at a low temperature, said heating being done at substantially a point location on said filament.

3. The method of treating a thermoplastic filament, comprising advancing the filament under tension over a roll, and applying heat to the exposed side of the filament at a point location thereon to heat said exposed side to a sufficient temperature to stress-relieve said exposed side, said roll being maintained at a temperature beneath the stress-relief temperature of the filament.

4. The method of texturizing a thermoplastic yarn, comprising advancing the yarn over a heat-sink element, and applying a stream of heated gas to the exposed side of the yarn at a point thereon to heat said exposed side to a temperature suflicient to stress-relieve said exposed side, said heat-sink element being cooled sufiiciently to maintain the other side of the yarn at a temperature below said stress-relief temperature.

5. The method of texturizing 'a thermoplastic yarn, comp-rising advancing the yarn across a heat-absorbing element at a speed within the range of 500-1500 feet per minute, and directing onto the yarn at the heat-absorbing element a stream of gas heated to a temperature within the range of 600-1100 F., said stream of gas being applied to the yarn at substantially a point location thereon.

6. The method of texturizing a thermoplastic yarn comprising advancing the yarn under tension across a heatabsorbing element at a speed within the range of 500 1500 feet per minute, and applying a stream of gas to the yarn at a point of engagement with the heat-absorbing element, said stream of gas having a temperature sufliciently high to stress-relieve the exposed side of the filaments in the yarn, said heat-absorbing element being cool enough to prevent stress-relief in the side of the yarn in engagement with said element.

References Cited by the Examiner UNITED STATES PATENTS 2,37 7,8 10 6/45 Robbins 28-82 2,708,813 5/55 Bourgeaux 18-54 2,774,126 12/56 Secrist 28--72.3 2,811,769 11/57 Craig 28-723 2,894,802 7/59 Braunlich 28--72 2,914,835 12/ 59 Slayter et al 28-72 2,917,805 12/59 Rokosz 2872 2,925,641 2/ 60 Evans 28-72 FOREIGN PATENTS 1,205,459 .8/59 France.

809,273 2/59 Great Britain.

MERVIN STEIN, Primary Examiner.

RUSSELL C. MADER, DONALD W. PARKER,

Examiners.

Claims (1)

1. THE METHOD OF TREATING A SYNTHETIC TEXTILE FILAMENT, COMPRISING PASSING THE FILAMENT THROUGH A TREATING ZONE UNDER TENSION, AND SIMULTANEOUSLY HEATING AND COOLING OPPOSITE SIDES OF THE FILAMENT IN SAID ZONE, SAID HEATING BEING DONE AT SUBSTANTIALLY A POINT LOCATION IN SAID ZONE,

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