US2803108A - Methods of processing textile yarns - Google Patents

Description

Aug; 20, 1957 N. J. STODDARD, ET AL 2,803,108

' METHODS OF PROCESSING TEXTILE YARNS Filed Jan. 4, 1954 3 Sheets-Sheet 1.

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Aug. 20, 1957 N. J. STODDARD ETAL 2,803,108

METHODS OF PROCESSING TEXTILE YARNS Filed Jan. 4, 1954 4 Y 5 Shee ts-Sheet 2 ,7 I II I r z' 'n' EESSSSHEjgE Eiiii 50 'I INVENTORS. 47 7 I] zvz'a/wzdsczsimdfim &

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N. J. STODDARD ET AL 2,803,108

METHODS 01 PROCESSING TEXTILE YARNS Aug. 20, 195? 3 Sheets-Sheet 3 Filed Jan. 4, 1954- mvm'oas: NICHOLAS J. STODDARD B WARREN A- SEEM WWW 4 W ATTYS.

United States Patent C) "ice METHODS or PROCESSING TEXTILE YARNS Nicholas J. Stoddard, Berwyn, and Warren A. Seem, Chester Springs, Pa., assignors, by mesne assignments, to Universal Winding Company, Cranston, R. 1., a corporation of Massachusetts Application January 4, 1954, Serial No. 401,803

11 Claims. (Cl. 57-157) This invention relates to thermoplastic textile yarns and methods of processing them. More particularly, it is concerned with polyamide and other thermoplastic yarns including nylon, Vinyon, Orlon, Velon, Dacron, Saran and the like (as distinguished from yarns of cotton, linen, rayon, silk, wool and the like), and to methods of thermally shrinking, thermally stretching, thermally processing and/ or thermally stabilizing such synthetic yarns by thermal treatment with incidental winding, twisting, twisting and untwisting, plying, coming, copping, nubbing, drying, dyeing, coating, singeing, sizing, and other normal processing operations, with the aforesaid thermal operations uniformly carried out to substantially whatever degree desired or required and simultaneously with normal yarn processing operations.

In processing polyamides and other thermoplastic chemicals of the kind referred to after conversion into yarns to render them suitable for use in weaving, knitting and other textile operations, it has been the common practise to utilize heat in many forms such as steam, hot liquids and hot vapors to thermally shrink, thermally stretch, thermally stabilize and otherwise thermally treat the yarn, all such operations being carried out before, after or between normal operation or as separate and independent, thermal operations. For example, to set the twist or stabilize the torsional forces after twisting, pretwisted thermoplastic yarns wound upon rigid or sometimes collapsible cores were heretofore placed in a heated chamber. On the other hand, to shrink thermoplastic yarns, they were subjected to heat after having been wound into skeins, or upon collapsible cores, or loosely upon rigid cores, and again subjected a second time to heat after rewinding. To stretch completed thermoplastic ply yarns or cords it has been necessary heretofore to resort to a separate thermal stretching operation, and for impartation of dimensional stability, to subjec the yarns to heat after winding upon a rigid core, and in some instances, to rewind and again heat treat the yarns.

It has also been the common practice in the past to wind thermoplastic yarns into skeins and to place the skeins into a closed heated treating chamber for shrinking and stabilizing the yarns. Here again, when the shrinkage desired was not consistent with the heat necessary for a relatively high amount necessary for thermal stabilization, and additional operations were therefore required in the processing. a

When thermoplastic yarns were shrunk as heretofore by subjection to heat after being wound upon collapsible cores, or after being loosely wound upon rigid cores with a second heat treatment after re-winding, one to four extra operations were involved in the treatment. Because of the rigidity of the cores, and the varying resistance to collapsing of the previously wound yarn layers, uneven shrinkage or contraction of the yarns took place throughout the packages, and, as a consequence the treated yarns varied in physical characteristics, i. e., in appearance, denier, size, dyeing properties, elongation, elasticity, strength, residual shrinkage, torsion and the like, these 7 2,833,108 Patented Aug. 20, 1957 variations and imperfections being carried through into the fabrics ultimately made from the yarn.

In the production of fish lines, nets and the like, for example, by prior art methods, the thermal stretching was done as a separate step after previous processing operations, but likewise without attainment of uniformity in the physical characteristics of the finished yarns.

In another prior art procedure for the purpose of attain ing dimensional stability, thermoplastic yarns wound upon rigid cores were heat treated, and sometimes again rewound upon rigid cores and again heat treated. Notwithstanding these heat treatments, the processed yarns lacked uniformity in physical characteristics due to uneven shrinkage as between the inner and outer windings of the yarns on the cores and subjection of the outer windings to the heat for a longer time period than the inner windings during each heat treatment.

Definite irregularities (such as in appearance, denier, size, dyeing properties, yield value, contractile force, elongation, elasticity, residual shrinkage, torsion, strength, and the like) exist in packaged thermoplastic yarns as they come from the producer. These irregularities are due to many uncontrollable conditions during initial conversion of the thermoplastic chemicals into yarn strands, i. e., they are occasioned by variations of tension in the spinning, stretching and packaging operations, by lengthening and/ or shortening of the yarns under changing conditions of temperature and humidity, and by variations in restraint upon the different layers of the yarns in the packages. Such imperfections cause, in fabrics and other products made from the yarns, corresponding irregularities which detracted from the appearance of the products, and frequently precluded use of the yarns in certain products of manufacture. In other cases the heretofore conventional yarn processing tended to accentuate the irregularities and/ or cause more pronounced imperfections which further impair the quality of the products manufactured from the yarns, or additionally precluded their use in certain products.

Subjection of thermoplastic yarns to high temperature for prolonged periods of time causes considerable heat degradation. For shrinking and/or stabilization of thermoplastic yarn in packages as has been the common practice heretofore, the packages were exposed in a heated chamber for an hour or more depending upon the size of the packages, the density of the windings and the circulation of the air in the chamber. It has been determined that the loss in tenacity of nylon yarn subjected to a temperature of 284 F. for prolonged periods varies roughly as the logarithm of the time exposure, and when subjected to this temperature for an hour the yarn loses about 4% in tenacity, in two hours it loses about 8%, and in eight hours it loses about 24%. Accordingly, when nylon or other thermoplastic yarns are treated by the usual prior art methods they vary in tenacity and in other physical characteristics from the inside to the outside of the packages.

' Thus, the processing of thermoplastic yarns by these prior art methods in preparation for weaving, knitting, or other uses entailed resort to numerous separate treating steps as well as frequent intermediate handlings of the yarns, all of which were painstaking, time consuming and expensive and so added very considerably to the cost of the yarns. Moreover, the results were generaly unsatisfactory from the standpoint of uniformity due to the difficulty of maintaining the temperature, to which the yarns were subjected, constant for a uniform time during the various separate treatments.

The chief aim of our invention is to overcome the herein pointed out drawbacks in the prior methods of processing thermoplastic yarns in preparation for use in the manufacture of woven, knitted and other textile prodnets, and to make possible the economic production of thermoplastic yarns which are uniform throughout as regards their physical characteristics. This objective is realized in practice, as hereinafter more fully disclosed, through provision of a simple and reliable method whereby improved uniformly processed thermoplastic yarns are produced in quantity in a rapid continuous manner at greatly reduced cost. Our method of processing provides the presence of heat and correlated yarn tension which we have discovered to be even more important for the best processing of thermoplastic yarn than the established practice of regulating relative humidity during the processing of other than thermoplastic yarns. This is broadly accomplished by introducing in the path of travel of the yarn during winding, twisting, twisting and untwisting, plying, coning, copping, nubbing, drying, dyeing, coating, singeing, sizing or the like, a thermally insulated regulatable restricted heated zone together with a regulatable yarn tension device; and then uniformly heating the traveling yarn under correlated tension.

Other objects and attendant advantages will appear from the following detailed description when considered in connection with the attached drawings, wherein:

Fig. 1 is a fragmentary view, in front elevation, of an exemplary apparatus suitable for processing thermoplastic yarns in accordance with our improved method.

Fig. 2 is a fragmentary view in vertical section, taken as indicated by the angled arrows II-li in Fig. 1 and drawn to a larger scale, showing one type of a specially designed heating device embodied in the apparatus.

Fig. 3 is a detail sectional view taken as indicated by the angled arrows lIilII in Fig. 2, and showing one type of a specially designed device by which the yarns are maintained under tension during the processing.

Fig. 4 is a view like Fig. 3, showing another form of a specially designed tensioning device.

Fig. 5 is a fragmentary view in front elevation of a modified form of the apparatus which is suitable for dyeing and chemically sizing thermoplastic yarns; and

Fig. 6 is a side elevational view of the apparatus disclosed in Fig. 5.

It is to be pointed out that we do not limit our process to the two types of tension devices shown in Fig. 3 and Fig. 4 since it is obvious that many variations in design are possible without departing from the invention. The basic requirement for a tensioning device to be utilized in our process is that it be capable of applying the re quired yarn tension uniformly.

The apparatus illustrated in Fig. 1 is basically what is ordinarily known in the textile art as an up-twister such as is commonly used in twisting operations, one of the usual multiple spindles for a wound package P of unprocessed yarn being indicated at 2, the traverse rail for the corresponding distributing guide 3 being indicated at 4, a usual drive roll for the collecting spool S being indicated at 6, and the rotary shaft of said roll being indicated at 7. Spindle 2 is rotated by tangential contact of its diametrically enlarged lower portion 8 with a running belt 9.

In converting the apparatus for the purposes of our invention, we arrange in the interval between the spindle 2 and the traverse guide 3, a heating device 10, and a yarn tensioning means 11 along the line of upward travel of the thermoplastic yarn Y, i. e., upwardly from the supply package P to the collecting spool S. As presently explained, the device 19 is electrically heated, current being conducted to it through two fixed horizontal bus bars 12 and 13 whereto said device is secured, with interposition of insulation bushings at 14, by screws 15 and 16 as best shown in Fig. 2. The required degree of heat is uniformly maintained in the device 10 by current at a constant voltage (not exceeding twenty-four volts for personal safety) through an automatic induction voltage regulator 17 from a power line 18, 19, said regulator being connected by conductors Zti, 21 to a manually adjustable 4. induction voltage regulator 22 connected in turn by conductors 23, 24 to the primary of a step down transformer 25 in circuit through conductors 26, 27 with the bus bars 12, 13. The output voltage of the induction voltage regulator 17 is automatically governed by a thermally responsive sensing means 23 incorporated in the heating device 1%. The automatic and the manual voltage regulators 17 and 22 and the thermostatic sensing means 28 may all be of any approved standard and commercially available types by cooperation of which the temperature in the heating device 10 is modulated compensatively with changes in ambient or room temperature and transfer of heat to the travelling yarn. Also included in the lines 18, 19 and 2t 21 respectively, are suitable manually operable safety hand switches 29 and 31).

As shown in Fig. 2, the heating device It comprises a central tube 32, of non-ferrous material and of small diameter and bore, through which the yarn Y is passed, said tube being exteriorly coated as at 33 with glass or other electrical insulation, and surrounded bya coil 34 of resistance wire. As further shown, tube 32 is embedded in a thick walled jacket 35 of thermal insulation which may be of fiber glass Sil-O-Cel granules or the like encased in a metallic shell 36. At its opposite ends, the shell 36 is closed by covers 37 which also may be of metal, with interposition between them and the heat insulating jacket material 35, of disks 38 of transite or the like to minimize thermal transfer from the hot tube 32 to said shell and vice versa. Engaged over the opposite ends of tube 32 and passing through the disks 38 are hard wear-resistant bushings 39 which may be of porcelain or the like, to prevent cutting of the tube by the yarn passing through it. It is to be particularly noted that the winding pitch of the heating coil 34 increases progressively from the bottom end of the tube 32 at which the yarn enters, to the mid height of the tube, and that it progressively decreases toward the end at which the yarn emerges. As a result, a greater amount of electric energy is available at the entrant and at the exit ends of tube 32, thereby making possible the maintenance of the desired uniform elevated temperature throughout the tube and the use of a much shorter tube than otherwise would be required. The lead it from one end of coil 34 is extended through the cover 37 to the screws 15, and the lead 41 from the other end of said coil to the screw 16. interposed in lead is a hand switch which is diagrammatically indicated at 42.

We do not limit our process to the use of the one design of heating device shown as 10 in Fig. 2 since it is obvious that many variations in design are possible without departing from the invention. The heating device shown as 10 in Fig. 2 is very practical for our process since it is capable of supplying uniform (11%) heat up to the melting point of the yarn without materially afiecting room temperature.

The tensioning or restraining means 11 comprises, in this instance, a small V grooved Wheel 45 about which one or more turns of the yarn Y are wrapped, said wheel being revolvable about the laterally bent end of a supporting shank member 46, and is engaged by a friction disk 47 which is backed by a compression spring 48, the force of the latter being finely regulatable by means of a thumb nut 49. As best shown in Figs. 2 and 3, the shank member 46 extends through a vertical slot 50 in a bracket bar 51 of metal suspended from bus bar 13, and is fixable after adjustment up or down and in and out by means of the clamp nuts indicated at 52. Arranged below the tensioning means 11 and similarly supported by the bracket bar 51 with capacity for both up and down and in and out adjustment is a pigtail guide 53 for the yarn Y, said guide being fixable in adjusted position by clamp nuts 54. 7

Again referring to Fig. 1, it will be noted that the thermoplastic yarn Y from the supply package 1 is threaded upwardly through one eye of the flyer 55 associated with spindle 2, then through the stationary guide 53, then one or more times about the wheel 45 of the tensioning means 11, then through the tube 32 of heating device 10, and finally through the traverse guide 3 enroute to the collecting spool S.

In the operation of the apparatus to carry out our improved processing method, the yarn Y is drawn upward at a uniform linear speed from the supply package P on spindle 2 by the pull of the rotating take-up spool S, being maintained all the while under a' predetermined constant tension by the tensioning device 11 in the interval between the latter and said take-up spool as it traverses the heating device 10. In the interval between the revolving supply package P and the wheel 45, the yarn is twisted by rotation of said package. As the yarn traverses the heating device immediately after being twisted, it is softened or plasticized, and by cooling, after emergence from said device on its way to take-up spool S, it is thermally stabilized and the twist, previously inserted, is set. By this it is meant that the yarn is yarn-set, that is, the molecules in the thermoplastic yarn are permanently and uniformly reoriented or realigned therein according to the physical configuration of the yarn at the time of yarn-setting so that the individual filaments of the yarn have an inherent tendency to retain or assume the physical configuration which they had at the time of yarn-setting. By adjusting the thumb nut 49 the resistance to free rotation of the wheel 45 can be varied to keep the tension at less than the contractile force of the yarn to shrink and stabilize the yarn, to maintain the tension equal to the contractile force of the yarn when stabilization only is desired, or to increase the tension beyond the contractile force of the yarn to stretch and stabilize it.

During the processing, the temperature in the heating device 10 is maintained at a definite prescribed degree, depending upon the adjustment of the manual induction voltage regulator 22, and modulated compensatively with changes in ambient or room temperature and transfer of heat to the travelling yarn through influence of the thermostatic sensing means 28 in said heating device upon the automatic induction voltage regulator 17. By reason of the thick thermal insulation surrounding the coil 34 of the heating device 10, a very little thermal transfer actually can take place between the yarn tube 32 and the outside atmosphere. As a consequence, the required degree of yarn treating temperature is uniformly maintained in the restricted zone defined by the heating device. By adjusting the tensioning device 11, the tension to which the yarn is subjected can be accurately correlated with the effective treating temperature and the constant linear speed of travel of the yarn under the pull of the rotating take-up spool S. It is to be understood that the temperature will be adjusted in accordance with the requirements of the particular kind of thermoplastic yarn which is to be processed, and the tension adjusted in accordance with the characteristics desired in the finished yarn.

The effect of heat upon the different thermoplastic yarns now in commercial use is generally known and can be readily determined for new thermoplastic yarns. For each particular thermoplastic yarn various temperatures have a definite effect upon shrinkage, stabilization, tenacity, yield under stress, contractile force, elasticity, breaking elongation and other physical characteristics. By correlation of a uniform prescribed heat and imposition of very little tension, in accordance with our invention, maximum shrinkage will be permitted to take place uniformly throughout the length of the yarn. By applying tension just equal in degree to the contractile force of the yarn at the given temperature, neither shrinkage or stretching will take place; while by applying high tension, maximum stretching will take place throughout the length of the yarn. Thermoplastic yarn treated in accordance with our new method takes dyes evenly, and greater permanency and depth of color result from the uniform heating at 6 the elevated temperatures with increase in tenacity and in the modulus of elasticity of certain types of thermoplastic yarns.

In carrying out our improved processing method it is essential, as already been pointed out, that the speed of linear travel of the yarn through the restricted heating zone 10 must bear a definite relation to the extent of heat transfer to the running yarn. We have found it to be a simple matter to predetermine the extent of thermal transfor in the restricted heating zone to a particular yarn at any given temperature and any given speed of travel. For example, with a temperature of 485 F. maintained in the heating zone, 200 denier nylon yarn run through said zone at the rate of 600 inches per minute Will shrink 8%. Since it is known that a dry temperature of 400 F. is required to shrink 200 denier nylon by the same amount, it is evident that the effective temperature in the heating device for that particular yarn and linear speed of travel must be 400 F. It is to be understood that by effective temperature we do not necessarily mean the temperature in the heating zone, but rather to the temperature required to obtain a given effect on the particular thermoplastic yarn involved if said yarn were not travelling but mearely heated to that temperature. Thus, by our improved method, it is possible to predetermine thermal shrinking, thermal stretching, thermal processing and/or thermal stabilization to any desired extent within the limits of the characteristics of the particular yarns, with or without incidental twisting as may be desired by regulation of the yarn tension and the temperature of the restricted heated zone. With many types of thermoplastic yarns, the presence of moisture adds substantially to the eflectiveness of the heat at a given temperature in the processing. To those familiar with the art, it will be evident that it is a simple matter to adequately wet out the running yarn with water or other liquid solution of effective chemicals prior to passage of the yarn through the restricted heating zone.

In our improved method of processing, it is no longer necessary to accept as unavoidable and to make the best of many of the undesirable and thermal characteristics of processed thermoplastic yarns. Rather, our improved method makes it possible to economically process thermoplastic yarns with utilization of the maximum thermal qualities and improvement of their physical properties.

A few examples are given below of the procedures followed according to our invention in the processing of thermoplastic yarns for different purposes and uses.

To prepare nylon yarn for use in the welts of ladies stockings, the manual voltage'regulator is adjusted to provide an effective temperature in the heating device 10 of'250 F. more or less depending upon the temperature used in subsequently preboarding of the hosiery in the usual way, adjusting the tensioning device, and running the yarn in the apparatus after the manner previously described, whereby the yarn is twisted, uniformly shrunk, stretched and/ or stabilized to the degree desired. Thermoplastic yarn so-processed will lend itself to be formed into uniform stitches by the needles of the knitting machines because it is set and molded to substantially smooth or rod shaped form. If, in the processing, the running nylon yarn is subjected to an effective temperature of 350 F. in the heating device, a tension of less than 0.4 gram per denier will cause the yarn to shrink while being twisted and thermally stabilized. Maintenance of a tension of more than 0.4 gram per denier, with other conditions remaining the same, will result in stretching of the yarn as it is twisted and stabilized; while under a tension of approximately 0.4 gram per denier, the yarn will simply be stabilized as it is twisted, without either shrinking or stretching. This continuous procedure is thus simple as compared with the prior art slow methods of thermoplastic hosiery welt yarn processing. which involved the separate stages of redrawing the nylon yarnfrom' the shipping bobbin or 7 pirn; uptwisting the yarn; reeling the yarn into a skein; shrinking the skein yarn while relaxed on a pole or wrapped in a bundle; backwinding the yarn; and finally coning the yarn.

To produce 30 turn 30 denier nylon leg yarn for ladies hosiery in accordance with our method, the twist setting or thermal stabilizing is accomplished simultaneously with uptwisting. In the usual prior art method of processing such yarn, the yarn was first twisted and spooled, and the spool placed for 90 minutes in a chamber wherein the atmosphere was heated to a dry bulb temperature of 170 F. and a wet bulb temperature of 160 F. to set the twist or thermally stabilize the yarn to prevent kinking or snarling in the knitting. Aside from being much more rapid, it will be seen that we have eliminated the double handling required by the prior art methods of preparing nylon leg yarn for ladies hosiery, the improved finished yarn being uniform in its physical characteristics and favoring the production of hosiery of improved attractive appearance, tit and length by reason of the uniformity of its stitches and residual shrinkage.

Another type of new and useful thermoplastic yarn can be produced in accordance with our invention by doubling and twisting two ends at low tension on a double-twister equipped with a heating unit constructed as hereinbefore described with an effective temperature of 400 F. maintained therein, one of the ends having had no previous thermal processing but the other end having previously been redrawn under tension through a similar heating unit installed in a conventional redraw machine also at 400 F. effective temperature. As a result of this processing, the end not previously thermally twisted, hrinks substantially and is wrapped by the other end which did not shrink, the finished yarn thus taking on a desirable cork screw appearance.

To produce a 100 denier 70 turn per inch nylon yarn having a sandy surface and substantially devoid of residual shrinkage, in accordance with our invention, we uptwist the yarn 70 turns per inch at 12,000 R. P. M. utilizing no flier and relying upon the ballooning, which takes place as the yarn is ravelled from the supply, to impart a low tension of approximately 7 grams. It will be seen that the sandy appearance of the yarn results as a consequence of this high twisting of the unheated yarn at the low tension. Yarn so twisted is then run in the apparatus of Fig. 1 with an effective temperature of 400 F. maintained in the restricted heating zone and thereby thermally shrunk, with attendant accentuation of the sandy appearance.

To produce 100 denier 70 turn per inch nylon yarn having a smooth surface and a dull appearance with substantially no residual shrinkage, the procedure followed is the same as in the example immediately above except for the substitution in the apparatus of Fig. 1 of the modified tensioning means 11a shown in Fig. 4. In this modified tensioning means, instead of a grooved wheel, a pair of opposing friction disk 45a are mounted for free rotation upon the laterally bent end of the shank member 46a. The yarn is passed between the disks 4511, one of the latter being yieldingly pressed toward the other by a spring 48a which is finely regulatable by a thumb screw 49a threadedly engaged upon the distal end of the shank member 46a. For the instant purpose, the spring 48a is adjusted to apply a tension of 80 grams upon the yarn as the latter passes between the disks 46a, this degree of tension being greater than the contractile force of the yarn while it is heated to the elevated temperature and is being twisted. This twisting and stretching causes the heated yarn to assume the desired smooth appearance and to have substantially no residual shrinkage.

To produce a 140 denier plied Dacron yarn, having a minimum of residualshrinkage and elongation as well as uniformity of other physical characteristics, in which two ends of 70 denier are each 5 twisted .24 turns 'per inch and Z twisted together 20 turns per inch, we first up-twist the respective ends in the apparatus of Fig. l with maintenance of an effective temperature of 350 F. in the heating device 10 and application of a tension of 70 grams to substantially stretch said ends and thermally stabilize their torsional forces. With this accomplished, we ply the two ends on a down spinner equipped with a similar heating device maintained at an effective temperature of 380 F. under a tension of grams to further stretch and stabilize the torsional forces, and finally up-twist the yarn 20 turns Z in the apparatus of Fig. 1 at a temperature of 400 F. at a tension of grams to still further stretch and thoroughly stabilize the yarn'dimensionally and torsionally. While a generally similar yarn could be produced by utilizing certain procedures known in the prior art, a great many more separate steps and intermediate handlings would have to be resorted to, but such yarn would lack uniformity in physical characteristics for the reasons previously pointed out.

To prepare thermoplastc yarns, suitable for tricot knitting, in accordance with our invention, We first wind the yarn from the producers delivery packages upon cones at an effective elevated temperature and under a tension consistent with optimum shrinkage and tenacity, by running them in a cone winder equipped with a heating device and a regulatable tensioning device like those described in connection with Fig. 1. In this example, only one normal operation is required. If the same requirements were to be met by prior art conventional methods, at least two additional costly operations would be involved namely, winding the yarn into a skein, and shrinking it while in the skein.

To produce uniformly dyed thermoplastic yarn, having maximum tenacity and a minimum of elongation on cones for use in circular knitting machines, the apparatus of Figs. 5 and 6 is utilized on which we cone wind the yarn from the producers package 201 in one operation by first passing it through a trough 202 containing a dye solution before running it through the yarn tension 203 and the heating device 204 and then winding it onto the constant thread speed cone take-up c, with the effective temperature and the tension so correlated as to obtain maximum stretch without loss of tenacity. In this example, the yarn Y is dried and the dye developed by the action of the effective elecated temperature during traverse of the yarn through the restricted heating zone. Production of such dyed yarns heretofore, required two separate operations to wit: thermal stretching of the yarn, and drying the yarn and developing the dye. Aside from being more costly than yarns produced according to our new method, the processed prior art dyed thermoplastic yarns lacked the desired uniform physical characteristics.

To produce a chemically sized highly twisted uniform nylon yarn with torisonal forces stabilized, in accordance with our new method, we run the yarn from a package 201a of highly twisted nylon yarn in a sizing machine as in Figs. 5 and 6 having a constant thread speed cone take-up c and heating and tensioning means like those in Figs. 5 and 6, utilizing an efitective temperature of 250 F. for stabilization, and a tension of 30 grams. The prior art production of yarns of this type entailed a separate stabilizing operation, and the desired uniformity as to characteristics could not be obtained due to irregular shrinkmg.

To produce a yarn of maximum strength in which an end of thermoplastic yarn is doubled or plied with an end of cotton, in accordance with our invention, we thermally stretch the thermoplastic end to obtain the same elongation at the breaking point as the cotton end runs the two ends together in the apparatus of Fig. 1, the thermal stretching being thus accomplished simultaneously with the plying. conventionally, several additional 9 operations would be required for attainment of corresponding results.

To produce substantially permanently set highly twisted thermoplastic yarn which is to be untwis-ted so as to become crimped, waved or flulfed, in accordance with our invention, we run the yarn continuously in a conventional up-twister equipped like the apparatus of Fig. l with a tensioning means and a heating device and subject the yarn to a high effective temperature and high tension whereby the thermal setting or stabilizing is accomplished simultaneously with the twisting.

To continuously produce permanently set highly twisted crimped, wavy or fluifed yarn in one continuous operation, according to our invention, we run the yarn in an up-twister equipped like the apparatus of Fig. l with a yarn tensioning means and a heating device, but with a special twisting and untwisting spindle such that the yarn is twisted while heated and then cooled, and the untwisting accomplished without interruption in the travel of the yarn. Such processing cannot be done, as far as we are aware, by any prior art method.

To process 70 denier nylon yarn, as received on a pirn from the manufacturer, for attainment of uniformity in appearance, denier size, dyeing properties, elongation, elasticity, residual shrinkage, etc., in accordance with our invention we unwind the yarn from the pirn instead of from a rotated package in the apparatus in Fig. l, and run it through the apparatus in the same manner as previously described with maintenance of a uniform effective temperature of 385 F. and a uniform tension between and 140 grams.

It is understood that the heating and tensioning devices herein shown are to be considered as exemplary of others which could be used providing that they are capable of maintaining the uniform temperatures and tensions necessary for attainment of the physical characteristics of our improved thermoplastic yarns.

From the foregoing it will be seen that we have provided a simple method by which various kinds of improved thermoplastic yarns for dilferent purposes can be thermally processed more rapidly and at a much lower cost than heretofore, with assurance of uniformity in appearance and other desired physical characteristics.

The illustrated apparatus, per se, forms the subject matter of a. separate patent application, Serial No. 401,952 concurrently filed herewith.

Having thus described our invention we claim:

1. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually passing the yarn at a selected linear speed under uniform tension through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to yarn-set the same, controlling the supply of heat energy to said zone to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension relative to the contractile force and thermal characteristics of the yarn resulting from heating the same.

2. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually passing the'yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passageunder tension through said heated zone, winding the processed yarn, maintaining the yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a selected uniform tension relative to the contractile force and thermal characteristics of the yarn resulting from heating thereof.

3. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually passing the yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to yarn-set the same, controlling the supply of heat energy to said zone com.- pensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension less than the contractile force of the yarn resulting from heating the same to shrink the yarn.

4. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually passing the yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension equal to the contractile force of the yarn to stabilize the same.

5. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually passing the yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension greater than the contractile force of the yarn to stretch and stabilize the same.

6. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually twisting the yarn, continually passing the yarn at a selected linear speed under uniform tension through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to reorient the molecules asoatos of the yarn to the' twisted formation ofthe yarnand yarn-set thesame, controlling the supplyof heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension relative to the contractile force and thermal characteristics of the yarn resulting from heating and twisting the same.

7. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually twisting the yarn, continually passing the twisted yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to reorient the molecules of the yarn to the twisted formation of the yarn and yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the twisted yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the twisted yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a selected uniform tension relative to the contractile force and thermal characteristics of the yarn resulting from heating and twisting the same.

8. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually twisting the yarn, continually passing the twisted yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to reorient the molecules of the yarn to the twisted formation of the yarn and yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the twisted yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the twisted yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension less than the contractile force of the yarn resulting from heating and twisting the same to shrink the same.

9. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually twisting the yarn, continually passing the twisted yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to reorient the molecules of the yarn to the twisted formation of the yarn and yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the twisted yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the twisted yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the twisted yarn at a uniform tension equal to the contractile force of the yarn to stabilize the same.

10. A method of thermally processing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually twisting the yarn, continually passing the twisted yarn at a selected linear speed through a restricted thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to reorient the molecules of the yarn to the twisted formation of the yarn and yarn-set the same, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the twisted yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, maintaining the twisted yarn under a uniform tension during heating, cooling and winding thereof, and correlating the tension in said yarn to said prescribed temperature and liner speed of travel of the yarn to maintain the twisted yarn at a uniform tension greater than the contractile force of the yarn to stretch and stabilize the same.

11. A method of thermally processing and dyeing thermoplastic yarn which comprises continually drawing the yarn from a source of supply, continually applying a dye to the yarn travelling at a selected linear speed, continually passing the yarn at a selected linear speed under uniform tension through a thermally isolated and uniformly heated zone to uniformly heat the yarn to a prescribed temperature to dry and uniformly develope the dye-stuif and yarn-set the yarn, controlling the supply of heat energy to said zone compensatively according to the ambient temperature and rate of transfer of heat to the yarn to thereby maintain said heated zone uniformly at the temperature required to uniformly heat said yarn to said prescribed temperature, continually cooling the yarn to stabilize the same after passage under tension through said heated zone, winding the processed yarn, and correlating the tension in said yarn to said prescribed temperature and linear speed of travel of the yarn to maintain the yarn at a uniform tension relative to the contractile force and thermal characteristics of the yarn resulting from heating the same and relative to the chemicalphysical properties of the dyestufi.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. 2. A METHOD OF THERMALLY PROCESSING THERMOPLASTIC YARN WHICH COMPRISES CONTINUALLY DRAWING THE YARN FROM A SOURCE OF SUPPLY, CONTINUALLY PASSING THE YARN AT A SELECTED LINEAR SPEED THROUGH A RESTRICTED THERMALLY ISOLATED AND UNIFORMLY HEATED ZONE TO UNIFORMLY HEAT THE YARN TO A PRESCRIBED TEMPERATURE TO YARN-SET THE SAME, CONTROLLING THE SUPPLY OF HEAT ENERGY TO SAID ZONE COMPENSATIVELY ACCORDING TO THE AMBIENT TEMPERATURE AND ATE OF TRANSFER OF HEAT TO THE YARN TO THEREBY MAINTAIN SAID HEATED ZONE UNIFORMLY AT THE TEMPERATURE REQUIRED TO UNIFORMLY HEAT SAID YARN TO SAID PRESCRIBED TEMPERATURE, CONTINUALLY COOLING THE YARN TO STABILIZE THE SAME AFTER PASSAGE UNDER TENSION THROUGH SAID HEATED ZONE, WINDING THE PROCESSED YARN, MAINTAINING THE YARN UNDER A UNIFORM TENSION DURING HEATING, COOLING AND WINDING THEREOF, AND CORRELATING THE TENSION IN SAID YARN TO SAID PRESCRIBED TEMPERATURE

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