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Publication numberUS3421194 A
Publication typeGrant
Publication dateJan 14, 1969
Filing dateOct 24, 1967
Priority dateOct 24, 1967
Publication numberUS 3421194 A, US 3421194A, US-A-3421194, US3421194 A, US3421194A
InventorsBreen Alvin L, Lauterbach Herbert G
Original AssigneeDu Pont
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process for treating a filamentary strand
US 3421194 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)




FIG. 4



REVERSAL POlNT 3 i L07; a z I a: w 0m 1 :2 2 REVERSAL E POINT E a I o a 2 s 4 5 e 1 2 s MC TENACITY, GPD

\k 5 FIG. l3 REVERSAL POINT l 74 4 V v 2 l i w z k 2 FILAIENT BREAK EwncmoM INVENTORS ALVIN L. BREEN HERBERT G. LAUTERBACH V ATTORNEY United States Patent 3,421,194 PROCESS FOR TREATING A FILAMENTARY STRAND Alvin L. Breen and Herbert G. Lauterbach, Wilmington,

Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Continuation-impart of applications Ser. No. 698,103, Nov. 22, 1957, and Ser. No. 70,269, Nov. 18, 1960.

This application Oct. 24, 1967, Ser. No. 684,583 US. Cl. 2872 4 Claims Int. Cl. D02g 3/02; D02j 1/00 ABSTRACT OF THE DISCLOSURE References to related applications This is a continuation-in-part of copending application Ser. No. 698,103 filed Nov. 22, 1957, and now abandoned, and of copending application Ser. No. 70,269 filed Nov. 18, 1960, as a continuation-in-part of application Ser. No. 842,524, filed Sept. 25, 1959, and both now abandoned.

This invention relates to a fluid treatment process for treating a filamentary strand such as yarn or thread to provide improved dyeability.

Artificial fibers are normally produced most easily as continuous filaments. These continuous filament yarns are very strong because of the absence of loose ends that are unable to transmit imposed stresses. Their extreme uniformity and lack of discontinuity, however, makes conventional continuous synthetic filament yarns much more dense than yarns made from synthetic staple fibers. The production of yarn from staple fibers, however, is time-consuming and requires a complex series of operations to crimp the fibers, align the fibers into an elongated bundle and then to draw the bundle to successively smaller diameters. The final spinning operation, which involves a high degree of twist, finally binds these discontinuous fibers together to produce a coherent yarn with consido erably increased bulk. The occulded air spaces give them a lightness, covering power, and warmth-giving bulk not normally possible with continuous filament yarns. Thus to get staple fibers that can be processed on conventional wool or cotton spinning equipment, it has been the practice to cut continuous filament yarns such as rayon, acetate, nylon, as well as the polyacrylic and polyester fibers into short lengths for spinning into staple yarn.

Recent developments in the textile industry have provided useful routes for improving the bulk and covering power and recoverable elongation of continuous filament yarns without resorting to the staple spinning systems of the prior art. A well-known process for making stretch yarn involves the steps of twisting, heat-setting and then backtwisting to a low final twist level. Another yarn of improved bulk is prepared commercially by the steps of twisting, heat-setting and backtwisting on-the-run using a false-twisting apparatus. This end product can be further modified by hot relaxing to improve the bulk and handle. Still another bulk yarn is being prepared by the wellknown stuffer box technique wherein the yarn is steamed ice to heat-set while it is in a compressed state in the stutter box.

All of these yarns of the prior art are produced by a process which has the common elements of deforming the yarn mechanically and then heat-setting either with or without an after-relaxation step. It was not until the recently disclosed product in US. Patent No. 2,783,609 issued Mar. 5, 1967, to Breen and its process of manufacture became known that an entirely new technique became available for improving the bulk of continuous filament yarns. This techniques involves exposing a filamentary material to a rapidly moving turbulent fluid, thereby inducing a multitude of crunodal filament loops at random intervals along the individual filaments. These loops and snarls of entangled loops increase the bulk of the continuous filament yarns considerably and result in fabrics of improved cover, bulk, handle, and the like. With the invention of Breen, a new tool is available for the bulking of filamentary structures, i.e., a turbulent fluid. Fluids, of course, have been used for yarn treating in many of the prior art operations such as drying, extracting, transporting, and the like. Until the invention of Breen, however, they had not been used to entangle, convolute, and bulk a filamentary material. It has now been discovered, however, that a new process utilizing the turbulent fluid technique results in new yarn products that have certain unique properties not heretofore disclosed in the art.

It is an object of the present invention to provide a process for treating a filamentary strand with fluid to provide improved properties, particularly with respect to dyeability. A further object is to provide such a proess for producing yarn with a combination of desirable tenacity and a high rate of dyeability. Other objects will become apparent from the disclosure.

According to this invention, there is provided a process for treating synthetic organic filamentary strands to provide products having a combination of desirable tenacity and a high rate of dyeability which has not been attained heretofore. These products are produced by feeding a synthetic organic filamentary strand at an overfeed of at least about 12% to a plasticizing stream of a compressible fluid in which the individual filaments, while in a plastic state, are momentarily separated from each other and then cooled. The stream of compressible fluid should be at a temperature above 275 F., preferably at least about 300 F., and temperatures of 400-600 F. are usually desirable. The strand may be cooled by passing through air at normal room temperature. The process makes possible a product which has high tenacity and also possesses a rate of dyeability at least about greater than that of the feed strand. By increasing the overfeed to at least 30%, preferably at least 40%, the filamentary product produced contains, in addition to the high tenacity and high rate of dyeability set forth above, fibers possessing an independent random, persistent, three-dimensional, non-helical, curvilinear configuration along the line of the filamentary strand and is substantially free of stable crunodal loops.

The invention and the manner of carrying it out will be more clearly understood by reference to the drawings in which,

FIGURE 1 is a schematic perspective view of apparatus suitable for the production of the improved yarn of this invention,

FIGURE 2 shows an alternate type of jet device for use in the apparatus of FIGURE 1,

FIGURE 3 is a schematic perspective view of equipment adapted to spinning, drawing and treating in successive steps without intermediate handling or packaging,

FIGURES 4, 5, 6, 7, 8, 9 and 10 show various jet devices useful in the production of the yarn of this invention,

FIGURE 11 shows a single filament produced in accordance with this invention from a fiber of non-round cross section,

FIGURE 12 shows a graphical relationship between the dye absorption and orientation angle of the product of this invention, and its tenacity, based on the data of Example I,

FIGURE '13 shows a graphical relationship of the pilling index of the product of this invention, and its break elongation, and

FIGURE 14 is a schematic representation of the structural characteristics of the filaments produced by this invention.

In FIGURE 1, the moving threadline 31 to be treated is passed through guide 32, between feed rolls 33 and 34, over guide 35, through fluid jet 36, over guide 37, through quench tube 38, provided with cooling fluid through opening 39, through guide 40, to guide 43, or alternately between feed rolls 41 and 42. Traverse guide 44 may be used to distribute the treated yarn on package 46 driven by roll 45 or package 46 may be a roll which with roll 45 is used to feed yarn to piddle tube 47 provided with aspirating tube 48 depositing yarn in container 49.

In FIGURE 3, filaments 70 from spinneret 71 quenched asymmetrically by cold fluid directed to the face of the spinneret by fluid nozzle 72 are converged at guide 73 and passed around rolls 74. The yarn is continuously drawn on draw pin 75 by wraps around rolls 76 moving at higher speed and is then fed through guides 78 and 79 and jet 80. The yarn leaving the jet is passed around guide 81 and rolls 82. Quenching device 84 cools the yarn or alternatively it is cooled by the flow of cold air through box 87 around cooling rolls 82, 85 and 86. From the cooling rolls, the yarn is fed continuously through traverse guide 88 to package 89 driven by roll 90.

FIGURE 6 is a jet suitable for the practice of this invention, consisting of body member 95, orifice member 96, held in place by clamp 97 and screw 98. This jet is illustrated more fully in Hall US. Patent No. 2,958,- 112 dated Nov. 1, 1960. The passage through orifice member 96 consists of cylindrical opening 100, connecting with concentric cylindrical opening 101, and outwardly tapered opening 99, characterized by the angle a. Yarn tube member 102, supporting hollow needle 103, in hole 104, with cutaway section giving a lip 105, is supported in body member 95, in an adjustable fashion by screw tightened in tapped hole 106. The compressible fluid is applied to the nozzle at 107 and the yarn is fed to needle member through hole 108.

FIGURE 7 is another jet consisting of body member 110, and yarn guide member 111, with perforated disc 112, and fluid entrance 113. Yarn is fed to this nozzle through opening 114.

FIGURE 2 is a similar jet particularly adaptable to multiple end operation where precise temperature control is desired from position to position. It consists of jet body 121, with opening 122 for the turbulent fluid, and replaceable orifice 123. Yarn guide member 124, provided with yarn opening 125, is machined so that tip 128 is eccentric to the jet axis. Jet body 121 is sealed in manifold 129 by gaskets 126 and flanges 127.

FIGURE 10 is a simplified jet suitable for the practice of this invention consisting of body member 130 with drilled holes as shown to provide a T-shaped intersection at 131. Thin-walled tubing 132 connecting to compressible fluid supply through adapter 133 serves as a combination conduit and heater for the compressible fluid. Similar thin-walled tubing 134 attached to body member 130 serving as a yarn preheater is provided .With yarn entrance 135. A high amperage electrical current applied between lugs 136 and 137 beats the compressible fluid passing through tube 132 by virtue of the electrical resistance of the tubing. Similarly, highamperage current applied between lugs 138 and 139 provides additional heating to the turbulent fluid exhausting in a counter-current direction to the thread line moving from toward 131. This arrangement preheats the yarn so that it is in a desirably plasticized state as it traverses the zone of greatest turbulence between 131 and 141. Turbulent fluid exhausting preferentially from orifice 141 produces the desired treating action. Insulation prevents excessive heat loss from tubes 132 and 134 and also tends to support these fragile elements. This unit .is particularly useful for treating yarns at very high speeds in the range of 500 1000 y.p.m. or more.

FIGURE 8 shows the intersection 131 of the jet in cross section of FIGURE 10. It is to be understood that other devices employing heated plates or rolls may be substituted for the preheater of FIGURE 10. Similarly, the preheating fluid could be a hot gas applied by an auxiliary nozzle or a hot liquid applied in an open bath or semi-confining tube. Such devices likewise may be made as an integral part of any of the fluid nozzles of FIGURES 2, 6, 7 or 9, or those described, for example, in Hall US. Patent No. 2,958,112 dated Nov. 1, 1960, and U.S. Patent No. 2,783,609 to Breen, issued Mar. 5, 1957.

FIGURE 9 shows one form of jet particularly useful for the practice of the process of this invention as indicated in FIGURE 3 where the thread line being treated is taken directly from a spinning operation. In this case, body member is split into two similar portions. Likewise, yarn guide member 143 is split into similar parts, laying open the yarn passage 144 and orifice 145. For stringup, these parts are held in the open position by hinge 146. During the treating operation, the parts are held in a closed position by hook 147 and pin 148. Screws 149 are used to adjust the depth of yarn guide member 143 within body piece 150. An adjustment of the opposing yarn guide members 143 to slightly differing depths produces a desirable eccentricity of the turbulent fluid flow pattern. Other forms of jets similar in principle to FIGURE 9 but having rotating or sliding parts or other mechanisms to provide access to the turbulent fluid chamber are likewise useful in the process of this invention.

For certain uses where enhanced luster and tactile dryness are desired the preferred product of this invention should be made from fibers having a non-round shape of critically selected character. In carpet yarns, for example, it has been found preferable to use non-round fibers of the type disclosed in US. Patent No. 2,939,202 issued June 7, 1960, to Holland.

An important property of products of this invention which is particularly noticeable with non-round fiber forms is illustrated in FIGURE 11. Here the fiber has not only a random, three-dimensional, non-helical, curvilinear configuration, but is also formed into a randomly twisted configuration, portions of which are in an S direction with other portions being in a Z direction. The twist is completely random along the length of the filament particularly with respect to 1) the angle of twist which varies continuously and randomly, (2) the number of twist reversals per inch of filament, and (3) the number of turns between twist reversals. Each filament contains at least 2 (absolute) turns per inch of twist (only full turns being counted).

It is very simple to observe filament twist in non-round filaments using conventional optical techniques. Filament twist in round fiber forms is also easily observed with an American Optical Baker Interference Microscope using techniques specified by the manufacturer in the operating manual for this microscope. To determine the extent of the random twist modification of the individual fiber, a specimen is mounted between microscope slides with sufficient tension to hold the fiber axis in an approximately straight condition (but a tension low enough that the twist is not appreciably reduced). The angle is then measured between imaginary lines following the outermost points of the filaments and the filament axis at a number of points sufficient to provide a meaningful average. This average angle should be at least 1. There will be points where the angle is essentially zero where the twist reverses direction. Other points are found where the angle is considerably greater than the average value. In well-modified samples maximum values in the order of 30 are observed and the average may be as much as 5 or more.

FIGURE 14 depicts a straightened filament c of this invention having a non-round cross section with e representing a single element on the surface of the filament (a line on the surface of the filament which, in the straight filament, prior to twisting or crimping of the filament, is straight and parallel to the axis of the filament). It will be noted that the direction of twist is alternately S and Z in adjacent sections of the filament. The angle of twist of the filament at any point h of element e is shown by alpha, the acute angle between a tangent t to element e at that point and plane i perpendicular to the plane of the paper) which contains both the axis of the filament and point h. In filaments of this invention, both crimped and uncrimped, the angle alpha varies continuously and randomly throughout the length of the filaments.

Since the twist of each filament is random along its length, a yarn made up of a group of these non-round filaments is prevented from packing in a closely nested configuration. This is true even when considerable tension is applied to the yarn sufficient to straighten any random curvilinear crimp configuration. This latter property is particularly useful in increasing the bulk of tightly woven fabrics where loom tension and fabric construction tends to reduce the bulking effect due to crimp. The random twist is likewise useful in highly crimped pile yarns or bulky knit structures where it tends to reduce objectionable glitter or luster associated with light reflection from the fiber surfaces.

In the preferred process of this invention, filaments and yarns meeting the above objects are provided by a process in which a stream of a compressible fluid at a temperature above 275 F. and above the second-order transition temperature of the polymer of which the filament is made, and preferably at least about 300 F., is vigorously jetted to form a turbulent plasticizing region. The yarn or filaments to be treated are positively fed at a rate greater than the yarn take-up Speed into the fluid plasticizing stream so that the yarn is supported by it and individual filaments are separated from each other and whipped about in the hot turbulent plasticizing region, and is then cooled while being maintained at low tension. Under these conditions the yarn temperature is above the cold poin as described more fully hereinafter and below the melting point of the yarn. During the jetting treatment, filament shrinkage occurs because of the heat transmitted to the fibers. The process elements such as temperature, pressure, fluid flow, yarn speed, tension and wind-up speed are adjusted so as to give a final yarn denier (measured in relaxed form after hot-wet relaxation) at least 12% greater than the feed yarn denier.

The treated yarn, of course, may be cut into staple after passing through the turbulent hot fluid. This process, therefore, provides a highly productive way of treating tow which is to be used in staple products. This process may also be used for setting dyes in the yarn.

A yarn padded with dyes may be either treated with a turbulent fluid to set the dyes in the fiber by diffusion through the fiber or it may be treated with 'a turbulent fluid to simultaneously bulk the yarn and set the dyes.

The process of this invention can be used to improve the properties of plasticizable fiber. The process is applicable primarily to continuous synthetic filament yarns and multifilament yarns in particular although \monofilaments can also be treated in the same manner. Staple synthetic yarns can also be processed to give products of improved dyeability.

The products of this invention are different in fundamental physical structure from any of the treated yarns described in prior art. During the jetting treatment, at least 12% lengthwise shrinkage of the filaments and substantial deorientation of the filaments occur. When jetted under optimum conditions, this shrinkage and relaxation far exceeds that which occurs when the yarn is exposed to the same fluid at the same temperature and under low tension for a long period of time without agitation. The instantaneous application of heat to fibers in the jet and extremely short exposure time permit deorientation to occur before substantial crystallization can occur. The yarn does not, therefore, become permanently set before deorienting and does not become brittle or weak. This dynamic relaxation is responsible for a considerable amount of deorientation of the molecules and an increase in crystallinity. In addition, there is a large increase in dye receptivity with little or no loss in tenacity. The improved combination of dyeability rate and tenacity of filaments of this invention can be expressed by the equation where D and D are the dyeability rates of the filament before and after shrinking, respectively, and T and T are the tenacities of the filament before and after shrinking, respectively. This relationship holds true for both crimped and uncrimped filaments of this invention. Generally, all filaments of this invention have a tenacity of at least 2 grams per denier.

The higher filament temperatures under relaxed conditions and the repeated stressing cause the amorphous molecular structure to open up giving more lateral space between molecules and greater distance between crystallites along the fiber axis. The great changes in the amorphous molecular structure are shown clearly by low angle X-ray patterns using the techniques described by W. O. Statton, I. Polymer Sci. 22, 385 (1956). This new openedup condition, plus the deorientation which occurs, gives fibers with greatly improved dyeing rate without substantial reduction in tenacity. The dyeing rate can be increased 75% to 250% by the process of this invention and there is no change in the chemical composition of the fiber during treatment. Of course, moderate improvements in dye rate have been shown in prior art by relaxed heat treatment, but such increases in dye rate with such small'losses in tenacity and with luster advantages due to random filament twist have not been known. In addition, the uniform turbulent heating in the present process permits much higher average filament temperatures to be obtained since there is no danger of surface filaments being heated above their melting point or fusing filaments.

All commercial procedures for manufacturing synthetic fibers inadvertently subject a portion of the yarn or certain segments of a portion of the yarn and filaments to plucks or other stresses as, for example, when processing with fluids or passing over guides, which causes these yarns or segments to dye at a different rate and/ or to a different depth relative to the bulk of the yarn. Prior art processes sometimes produce indentations along the filament length due to the pressing together of crossed filaments or result in bulging of the filament walls due to a sharp creasing of the filaments. The dynamic relaxation employed in this invention avoids these non-uniformities in structure and produces filaments with exceptional dyeability and tenacity but without cross-sectional configuration distortions. The yarns produced by this invention thus are uniform in cross section, a characteristic particularly noticeable with round filaments. The yarns prepared by the process of this invention also have better dyeing uniformity than bulk yarns prepared by the twist-heat set method, by stutter-box crimping, or by other similar prior art crimping methods which produce filament distortion during the crimping process.

The process of this invention can be used to prepare such improved products from any natural or synthetic plasticizable filamentary material. Exemplary thermoplastic materials include polyamides, e.g., poly(epsilon caproamide) and poly(hexamethylene adipamide) cellulose esters, e.g., cellulose acetate; polyesters, particularly polyesters of terephthalic acid or isophthalic acid and a lower glycol, e.g., poly(ethylene terephthalate), poly(hexahydro-p-xylylene terephthalate); polyalkylenes, e.g., polyethylene, linear polypropylene, etc.; polyvinyls and polyacrylics, e.g., polyacrylonitrile, as well as copolymers of acrylonitrile and other copolymerizable monomers can be treated to give the improvement in properties discussed, and particularly in dyeability. Copolymers of ethylene terephthalate containing less than 15% combined monomers other than ethylene terephthalate and copolymerizable with ethylene terephthalate are suitable. Spandex fiber properties are also improved. While the preferred form of material is continuous filaments, the process and resultant improvements occur with staple yarns as well.

The process is useful for treating both monofilament and multifilament yarns in textile deniers as well as the heavier carpet and industrial yarn sizes either singly or combined in the form of a heavy tow. Fine count and heavy count staple yarns can be processed both singles and plied. The process and product are also not restricted in the case of the synthetic materials to any one particular type of filament cross section. Cruciform, Y-shaped, deltashaped, ribbon, and dumbbell and other such filamentary cross sections can be processed at least as well as round filaments and usually contribute still more bulk than is obtained with round filaments.

The turbulent fluid used to treat the filamentary material may be air, steam, or any other compressible fluid or vapor capable of plasticizing action on the yarn provided that it has a temperature above 275 F. and above the second-order transition temperature of the filament. Hot air will give suflicient plasticization in the turbulent region for many fibers although it may be desirable for certain fibers to supplement the temperature effect with an auxiliary plasticizing medium. Actually, steam is preferentially used in the subject process since it is a cheap and convenient source of a high pressure fluid with a compound plasticizing action.

The temperature of the fluid medium must be regulated so that the yarn temperature does not reach the melting point of the fiber. However, with fibers made from fusible polymers, the most effective treatment and greatest productivity is obtained when the temperature of the turbulent fluid is above the melting point of the fiber. In this case the yarn speeds should be great enough so that melting does not occur. Because of thegreat turbulence and the high heat, yarns are heated rapidly. Temperatures below 275 F. and lower than the second-order transition temperature (T of the yarn material should usually not be employed because under these conditions the dyeability of the filaments is not improved and the utility of the fibers is reduced.

One of the essential elements of the process is that the filaments or yarn must be inherently elastic but must be rendered non-elastic and plastic in the turbulent atmosphere. The plastic condition may be brought about by the temperature of the compressible fluid. In any case, the plastic condition of the filaments must be temporary and transitory. The term plasticizing or plastic is intended to mean that the conditions to which the term relates are such that the filaments are in a temporarily flaccid, nonelastic, deformable condition. After the plasticizing conditions are removed such as by lowering the temperature, chilling, removing the solvent, or similar considerations, the filaments and yarns must return to their normal elastic state. The use of an inert compressible fluid such as air or steam under conditions which do not plasticize, soften, or render the filaments non-elastic, does not fall Within the scope of the invention. Wet steam will fail to produce the improvements in the yarn described above if the temperature of the yarn does not reach a point sufliciently high to render it plastic and non-elastic. On the other hand, relatively low temperatures may be used if there is suflicient residual volatile solvent in the filaments. It will also be apparent that large amounts of non-volatile plasticizers such as dibutyl phthalate, tricresyl phosphate, oils, plasticizing resins, etc., are relatively permanent, and when these are present, the yarns will not return to an elastic condition and should be avoided except for special purposes.

At high speeds and with certain polymers the fiber temperature should be well above the second-order transition temperature. A preferred minimum temperature defined as a cold point is given by J. W. Ballou and J. C. Smith in the Journal of Applied Physics, volume 20, page 499 (1949). The cold point is the second inflection in the sonic modulus-temperature curve for the polymer or fiber in question. In general, this temperature may be 50 C. or more above the second-order transition temperatur The temperature of the filamentary structure is difficult to measure under the usual working conditions. At high speed it is indicated that the surface temperature of the fiber being treated may be well above the temperature of the fiber interior. At low speeds, however, the filamentary structure tends to come to equilibrium with the turbulent fluid temperature. The minimum temperature useful for treating the filamentary structure at low speeds in the range of 1 to 5 y.p.m. may be considered the minimum useful yarn temperature for the process of this invention.

Yarn feed speed can be varied over a considerable range depending on the material, temperature, denier, degree of bulking, tension and other variables. For economic reasons (productivity/position) the feed rate should be at least 30 y.p.m. although slower speeds may be used for specific items or special effect. Feed rates can run as high as 5000 y.p.m. or even higher. Preferred feed rates are in the range of 300 to 3500 y.p.m.

The temperature of the heating fluid must be high enough so that either alone Or in combination with some auxiliary plasticizing component, e.g. water, acetone or other solvent, it will soften or plasticize the filamentary material passing through the heating area. The optimum temperature, of course, varies depending upon the material being treated, the form of the material being treated; i.e., staple or continuous filament, the denier or yarn size, the rate of throughput, the degree of turbulence and/or pressure of the treating fluid, the design of the treating chamber, annd the extent of treatment desired. The temperature can range as high as 700 F. or more and a preferred range is 400-600 F. The controlling factors are the characteristics of the material being treated and the temperature actually reached by the filamentary material during treatment. The true upper limit, of course, is the temperature at which objectionable melting and/or chemical degradation of a given yarn takes place.

There are a number of means and apparatus whereby a turbulent stream of fluid can be produced. Suitable jets or devices for treating a filamentary material with a turbulent plasticizing fluid to achieve the improvements of this invention are described in US. Patents Nos. 2,783,609 and 2,852,906 to Breen, and US. Patent No. 2,958,112 to Hall, as Well as those disclosed herein. After cooling, the yarn can "be subjected to normal processing tensions and wound into any of the conventional yarn packages. This cooling operation can be carried out by piddling into a sliver can or onto a moving belt or screen but from an economic viewpoint, it is preferred to cool the yarn on-the-run as an integral element of the overall crimping or bulking process. It is preferred to use a positive cooling operation either immediately before or after the take-up roll-the important factor is that cooling is effected prior to imposing any substantial tension on the hot plastic crimped filamentary material.

Adequate cooling of the yarn can be achieved by passage across a chilled plate or roll. Passage of the yarn through a suitable liquid bath will also cool the yarn adequately. The preferred embodiment, however, is the use of a flow of a cooling fluid preferably a gas. This can be in the form of a jet that impinges the gas on the yarn bundle or it can take the form of the jets described previously for treating the yarn with a hot turbulent plasticizing medium. Cooling jets can be designed to forward the yarn, apply a braking action, or so designed and balanced that they exert neither a forwarding action nor a braking action.

The feed pressure of the hot plasticizing fluid will depend on the degree of turbulence desired, feed speed, yarn denier, material being processed, design of jet and the like. Pressures in the range of 20 p.s.i.g. to 200 p.s.i.g. or more are useful while the preferred range is from 40-100 p.s.i.g. Normally economics will dictate that the optimum pressure is the lowest that still gives the desired treatment.

In US. Patent No. 2,783,609 it is disclosed that the filamentary material should be removed abruptly from the fluid stream. It has been found advantageous in the subject process to remove the filaments gradually from the hot fluid stream thus keeping the yarn hot for a longer period of time prior to quenching. The rapidly expanding fluid medium will also give a cooling action outside of the yarn heating zone.

The process is well adapted for using a number of ends of yarn in the same jet. Thus, it is possible to pass two to five or more ends through a single jet at the same time. The resulting yarn may have the ends well blended or it may have treated ends which will be distinctly separate and independently windable depending on the proc essing conditions. Two or more yarns may also be treated using different tensions or feed rates so as to produce a tension-stable yarn with extensibility confined to that of the shorter member. Likewise, two different types of yarn such as nylon and rayon may be passed through the jet. The differential shrinkage and heat-setting of the two types of yarn provide many interesting effects which are desirable for aesthetic reasons in textile materials. It is also to be understood that any treatment of yarns herein disclosed is to be construed as being applicable also to single filaments although for reasons of economy bundles of filaments or yarns are treated. The term yarn refers to anylong or continuous length of a bundle of filaments.

The synthetic filamentary materials to be treated by the process of this invention should preferably be in a high state of orientation to reduce pilling in the finished fabrics. Drawable filaments tend to snag and pull out of the fabrics. The resulting fuzz fibers then tend to wind up into fuzz balls usually referred to as pills in the finished fabric. When the oriented filamentary structures are passed under low tension through the hot turbulent plasticizing fluid medium, a considerable degree of deorientation and crystallization occurs.

Because of the unusually large increase in crystallinity, during processing, the final yarns have a break elongation that is much smaller than would be expected considering the large decrease in orientation. Similarly, the tenacity changes less than expected. At the same time, the yarns have a surprisingly high dyeing rate. The net result is to obtain unusual yarns having a desirable combination of low elongation, low pilling tendency, and rapid dyeability. Pilling is avoided because yarns of low elongation do not easily draw or pull out of the yarn or fabric when snagged to give long fuzz fibers. These undesirable fuzz fibers cause pilling by winding and entangling around one another until balls of fuzz are formed. Of course, yarns with low elongations can be obtained in other bulk yarn processes by drawing the feed yarn adequately, but these highly drawn yarns then have relatively low dyeing rates.

The high degree of deorientation that accompanies the relaxation in a preferred process results in a gross increase in the filament denier of the yarn being treated. Some increase in denier, of course, accompanies almost any relaxation or bulking process, i.e., 110%. The filament denier of the new products formed by the subject process, however, increases in denier from 12 to 25% or more as compared to the filament denier prior to treatment. In this instance, of course, denier is measured by the change in filament weight per unit length with any crimp removed by a light tension, eliminating the denier increase associated with crimp contraction.

Since it is likewise desirable that true fiber shrinkage accompanied by molecular deorientation be accomplished, this shrinkage has been determined as follows:

Percent shrinkage= [1 Dem ]X D6D0 1 where Den is the denier of the yarn before treatment.

In order that the greatly improved dyeability may be achieved at acceptably low yarn elongation values, it isnecessary that the true fiber shrinkage accompanying this process be at least 12% and preferably 25% or more.

Another parameter derived from the above measurements is useful in comparing yarns made at uncontrolled overfeed (FIGURE 1 without rolls 41, 42, 45, and 46), with those made with the double roll or triple roll systems (FIGURE 1 as shown). This has been termed the effective overfeed (EOF) and is calculated as follows:

All of the jets useful in the process of this invention are characterized by an arrangement for the common exit of the turbulent fluid and the yarn bundle being treated. The turbulent fiuid in all cases exhausts at high velocity relative to the yarn velocity. One surprising quality common to all jets which are adjustable is the need for careful adjustment of the jet for optimum treatment. The jet shown in FIGURE 6 is easily adjusted by moving part 102 in or out with respect to part 95. A second adjustment is accomplished with the rotation of part 102 within the opening 104. In general, with heavy weight yarns, lip 105, on needle 103, should be withdrawn from the center position. For light denier yarns the optimum adjustment is with the lip beyond the center line of opening 100. The needle obstruction in the air flow also adds turbulence to the system which in some cases gives a superior product.

Jets shown in FIGURES 2, 7, and 9 are also sensitive to adjustment. In general, the part (111, 124, or 143) introducing the yarn to the air stream should be slightly offcenter with respect to the orifice axis for best action. A 60 angle 0: (FIGURE 6) favored ease of adjustment for best action. In the jet of FIGURE 10 the eccentricity factor is provided by the abrupt change of direction of the high velocity fluid as it enters the yarn passage from one side. A variation of this apparatus having several fluid entry ports spread about the periphery of the yarn passageway is likewise made eccentric in its action on the yarn by using ports of different sizes and/ or by disposing them in a preferred unsymmetrical grouping. Stationary baifies within the jet may be used similarly to provide the eccentric flow pattern.

The dyeing rates for feed and jet processed yarns are determined by analyzing the dye baths or fibers. The amount of dye in the fiber is determined after dyeing for a short interval at a given temperature. Complete dye rate curves can be obtained by dyeing a number of separate samples each for different lengths of time. For the purpose of this invention, however, the dye rate is defined as the amount of dye absorbed by the fiber in ten minutes at a given temperature. Each fiber sample is dyed in a separate dye bath. The percent dye in the fiber may be determined by ultraviolet spectral analysis of the dye bath or of a solution obtained by extracting dye from the fiber. The ratio by Weight of dye bath to yarn is 400: 1.

Slightly different methods are used for acid-dyeable polymers, basic dyeable polymers and those which dye with neither acidic nor basic dyes. Yarns having basic sites in the polymer such as the polyamide yarns, 6 and 66 nylon, are dyed at 140 F. for ten minutes with 8% acetic acid and 4% Du Pont Anthraquinone Blue SWF based on weight of fiber. Anthraquinone Blue SWF is Acid Blue 165 of the Colour Index, Society of Dyers and Colourists and American Association of Textile Chemists and Colorists, 195 6. The percent dye in fiber is calculated from the percent in the dye bath based on light transmission at Wave lengths of 595 millimicrons. The initial dye bath with a known amount of dye serves as the standard sample for calculating concentration of dye in unknown solutions after dyeing. The dye baths, including the standard, are diluted two-fold before measuring transmission. The concentrations of dye in the bath are calculated from percent transmission by the use of Lamberts Law.

Yarns having acidic sites in the polymer such as modified polyethylene terephthalates containing 2% or more of a sulfoisophthalic ester are dyed using 4% Du Pont Sevron Blue 5G and 4% Acetic Acid for minutes at the boil in the absence of carriers. The percent dye in the fiber is calculated from the percent dye in the bath using the transmission at 660 millimicrons. The bath is diluted tenfold for this determination.

Yarns which do not have acidic or basic sites, such as unmodified polyethylene terephthalate, are dyed with a dispersed color in the absence of carriers. It is desirable to use a color which is sensitive to physical changes in the fibers. The polymers with no acidic or basic groups are dyed, therefore, with 4% Latyl Violet BN and 2% sodium lauryl sulfate dispersing agent based on fiber weight for 10 minutes at the boil without carrier to establish the dye rate. After drying, fiber samples weighing 0.5 g. are analyzed for percent dye by extracting several times with chlorobenzene at 100 C. for about 5 minutes. The combined extracts are then diluted to a total volume of 100 ml. Analysis is made 'by using an ultraviolet spectrophotometer -at 580 millimicron wave lengths.

The steam treated yarns and the feed yarns are examined by standard X-ray diffraction techniques after relaxed boil-off. Methods for determining orientation angle are described by W. A. Sisson in the Journal of Textile Research, 7, 425 (1937) or Ingersoll, H. G., J. Appl. Phys. 17, 924 (1946). For the purposes of this invention, fibers are mounted for X-ray examination with 0.015 g.p.d. tension applied to remove substantially all crimp during exposure. The orientation angle is defined here in terms of the azimuthal width of an intense equatorial diffraction are. The angle is the width in degrees between the two points midway the peak intensity and the background intensity. This parameter decreases in value as orientation increases.

Higher temperature of the turbulent fluid tends to give higher orientation angles (low crystalline orientation). Orientation angles as high as 40 have been obtained by the process of this invention. It is preferred that the treated yarn have an orientation angle greater than that of the feed yarn. Orientation angles for 6 nylon are obtained in the range 13 to 35 degrees by varying the process condition. For 66 nylon the orientation angle ranges from 13 to 40 degrees and for polyethylene terephthalate homopolymer orientation angles are obtained in the range 24 to 50 degrees. The basic-dyeable polyethylene terephthalates obtained by copolymerization of terephthalate esters with sulfoisophthalic esters likewise deorient in this bulking process, and orientation angles of 22 to 50 degrees are obtained. Yarns from crystallizable polymers have greatly increased cryst'allinity after treating in the hot turbulent jet.

A surprising feature in the products of this invention is the combination of high dyeability and tenacity and low orientation (high orientation angle). Otherknown processes (e.g., British Patents 684,046 and 735,171) give high tenacity even though the filaments are deoriented, but these other processes result in yarns with filaments stuck together and with no crimp and without the improvement in dye-ability of filaments of this invention.

If the overfeed is kept low enough at any given set of processing conditions, uncrimped yarns with random S and Z filament twist may then be obtained by the process of this invention. These uncrimped yarns are superior to other heat relaxed yarns since in addition to the novel twist the filaments do not stick together and have very high dye rate and high tenacity.

Additional information may be obtained by studyiii g low angle X-ray patterns by the method of W. O. Statton (J. Polymer Sci. 22, 385 (1956), Crystallite Regularity and Void Content in Cellulosic Fibers as Shown by Small Angle X-Ray Scattering). The low angle pattern shows a higher amount of crystallite placement regularity in the bulked yarns of this invention compared to the feed yarns. At the same time there is a great increase in the size of the long period. A typical steam bulked 66 nylon yarn, for example, had a long period of 98 A. while the feed yarn had a long period of only 86 A. Higher temperatures and longer exposures to hot fluids in the jets give greater long periods. It is preferred that the treated yarn have a long period at least 4 A. greater than the feed yarn. By the process of this invention, filaments of various polymers having long periods in the following ranges are obtained: 66 nylon, 75-100 A.; polyethylene terephthalate, 95-140 A.; 6 nylon, 110 A.; copolymers of polyethylene terephthalate, l40 A.

According to this invention there are produced filaments having outstanding tenacity and very high dyeability, for example, poly(hexamethylene adipamide) having a long period of at least 90 A., a tenacity (T of at least 3.0 and an orientation angle of at least (23.51.4T poly(epsilon caproamide), said filament having a long period of at least 92 A., a tenacity (T of at least 2.5 and an orientation angle of at least (150.30T poly(ethylene terephthalate), said filament having a long period of at least A., a tenacity (T of at least 1.0 and an orientation angle of at least (474.0T and copolymers of ethylene terephthalate containing less than about 10% combined monomers other than ethylene terephthalate and copolymerizable with ethylene terephthalate, said filament having a long period of at least 110 A., a tenacity (T of at least 1.0 and an orientation angle of at least (28-2.3T

The following examples illustrate embodiments of the process of this invention and the products obtained. It is to be understood that while they illustrate the use of certain synthetic polymeric yarns having certain cross sections these may be substituted by any other polymeric yarn or filament herein disclosed having any cross section such as circular, square, rectangular, flat, star-shaped, or those having three or more cusps and similar shapes. Likewise the denier, speed, temperature, take-up speed, and other considerations may vary widely within the limits given above.

All of the filaments produced by the process embodiments illustnated in the following examples have completely random S and Z twist as described heretofore.

EXAMPLE I th an acid dye (Du Pont Anthraquinone Blue SWF) increased from 0.42% in minutes for the feed yarn to 1.43% for the 450 F. bulked yarn. The orientation angles increase using steam at three difie d from 13.0 degrees to 20.8 degrees as the temperature increased to 450 F.

zero-twist semi-dull yarn with round filament cross section. Each of the yarns was processed using 500 yardsper-minute feed speed and 55 p.s.i. steam. Very moderate crimp was obtained at 300 F., but at the higher temperatures, such as 610 F. and 660 F., excellent crimp was obtained, and the dye rates were very greatly increased. The bulked yarns were dyed with Latyl Violet BN, a dispersed dye, in the absence of carrier. Autoclaved samples, on the other hand, had greatly reduced dye rate after treatment at 275 F., 325 F., or 350 F. The orientation angles increased for the autoclaved yarns and for jet treated yarns, but only the jet treated yarns had the combination of good crimp, high dye rate, and high tenacity. The jet of FIGURE 1 is described in detail in Hall U.S.

Other samples of the same feed yarn were treated by lrn- Patent No. 2,958,112.

TABLE II Dye rate Filament tensile properties (boiled off) dispersed Orientation Yarn treatment dye (percent Denier per angle absorbed in Ten, Elong, Mi, filament (deg.) 2

10 min. at g.p.d. percent g.p.d., (d.p.t.)

boil) Feed yarn 1.02 4. 7 48 59 2. 2 25 Jet, 300 F., 19% overfeed 0. 33 4. 8 44 60 2. 2 Jet, 400 F., 27% overieed 0.57 4. 6 54 50 2. 3 Jet, 500 F., 42% overfeed 1. 06 4. 2 75 33 2. 5 24. 1 Jet, 610 I 2, 80% over-feed... 1. 41 3.1 127 16 3. 2 Jet, 660 F., 125% overfeed 2. 32 2. 8 126 21 3. 2 43. 6 Autoclave, 275 F., minutes, H20. 0 25 4. 8 60 55 2. 2 Autoclave, 325 F., 15 minutes, H20. 0. 26 4. 5 53 54 2. 3 Autoclave, 350 F., 15 minutes, 1110. 0. 08 4. 1 45 57 2. 4 18. 4

1 Mi is initial modulus which is the slop val (load in grams/denier v 1 Measured using 100 diffraction spot 15 minutes at 275 F. or 325 F. in a sealed autoclave. There was a drastic reduction in tenacity to 1.4 grams per denier in the autoclaved sample prepared at 325 F. The dye rate for the autoclaved yarn increased to 1.20% for the sample treated at 325 F. The autoclaved yarns had no crimp even though the orientation angle increased greatly. The data show that the yarns of this invention have the rate combination of high tenacity and high dye rate. At the same time, these yarns may be produced with curvilinear crimp. The amount of crimp and the dye rate each increased as the jet temperature increased. The data from this experiment are shown graphically in FIGURE 12 where line A represents autoclaved yarn and line B refers to bulked yarn prepared 45 in a steam jet.

mersing in water for e of the straight line portion of stress-strain curves beyond the point 01 s. fractional elongation).

EXAMPLE III A modified polyethylene terephthalate yarn having 2.0% sulfoisophthalic ester in the polymer was treated as shown in Table V. The feed yarn was a single end of 70-denier, SO-filament, zero-twist, semi-dull yarn having filaments with triangular cross section. All of the yarns were processed in the jet at 500 y.p.m. and p.s.i. steam pressure. Moderately crimped filaments were obtained at the lower temperatures. Very highly crimped filaments were obtained from the jet treatment at 500 F. The treated yarns were dyed with basic dyes and the dye rate increased very greatly for the 500 F. samples. This increase in dye rate was obtained without appreciable loss TABLE I Dye rate Filament tensile properties (boiled ofi) acid dye Orien- Yarn treatment (percent Denier tation absorbed Ten., Elong, Mi, per angle in 10 min. g.p.d. percent g.p.d. filament (deg) I at 140 F.) (d.p.f Feed yarn 0. 42 6.0 36 29 15. 8 13. 0 Jet, 275 F., 40% 0v 0.55 6. 5 38 25 15. 7 13. 3 Jet, 325 F., 40% 0v 0. 71 7.1 45 24 15.3 14. 4 Jet, 450 F., 100% overteed 1. 43 5.0 98 8. 5 19. 7 20. 8 Autoclave, 275 F., 15 minutes, H20. 0 83 5. 7 108 26 14. 8 14.4 Autoclave, 325 F., 15 minutes, H20. 1 20 l. 4 23 21 18. 7 18. 6

1 Measured using 100 difiraction spot.

EXAMPLE I1 A single end of continuous filament yarn spun from polyethylene terephthalate was bulked using the jet of FIGURE 1. The feed yarn was a -denier, 34-filament,

in tenacity. On the other hand, yarns which were treated in the autoclave, as shown in the table, had much lower dye rates and were not crimped.

TABLE III Dye rate Filament tensile properties (boiled ofi) Orienbasic dye tation Long. Yarn treatment (percent ab- 'Ien., Elong, Mi. Denier per angle period (A.)

sorbed in 10 g.p.d. percent g.p.d. filament (deg) min. at boil) (d.p.f.) Feed yarn 1. 26 3. 2 61 44 1. 5 18. 5 9 Jet, 300 F., 19% overfeedun 0.90 3. 3 52 48 1. 6 22. 7 98 Jet, 400 F., 35% overieed 1. 24 2. 8 59 43 1. 6 Jet, 500 F., 145% overieed l 2. 50 2. 6 91 25 2.0 24. 7 122 Autoclave, 275 F., 15 minutes, H 0. 16 2. 6 25 50 1. 4 Autoclave, 325 F., 15 minutes, H10. 0. 66 2. 0 16 59 1. 4 15. 1 102 1 Mi is initial modulus (load in grams/denier vs. fractional elongation).

2 Measured using difiraction spot.

which is the slope of the straight line portion of stress-strain curves beyond the point of crim p removal EXAMPLE IV Two ends of a continuous filament polyhexamethylene adipamide yarn were processed in the jet 'of FIGURE 1,

using three different overfeeds as shown in Table IV. The yarn was 780-denier, 51-filament, 0.75 Z twist bright nylon with round filament cross section. Each of the yarns was processed at 108 yards-per-minute feed speed and 85 p.s.i. steam pressure. In each case, the steam temperature was 450 F. The dye rates, tensile properties, and orientation angles for the processed yarns are shown in Table IV. The yarn which was processed with 22% over feed was an uncrimped straight yarn and had very greatly increased dye rate over the feed yarn. The yarn processed at 40% overfeed had curvilinear crimp in the filaments and had still higher dye rate. The yarn processed with 100% overfeed was a highly bulked yarn with excellent crimp, high dye rate, and good tensile properties.

16 tained having a dye rate with Du Pont Anthraquinone Blue SWF, an acid dye, of 2.0% dye in 10 minutes. The filaments were not crimped. It had a tenacity of 3.9 g.p.d. The orientation angle was 17 degrees.

Since many difierent embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

We claim:

1. A process for treating a synthetic organic filamentary strand to provide improved dyeability at high tenacity without imparting curvilinear filament crimp which comprises feeding the strand at a rate of at least yards per minute to a plasticizing stream of compressible fluid having a temperature of at least 275 F. and sufficient velocity to momentarily separate the filaments, treating TABLE IV Dye rate Filament tensile properties (boiled ofi) acid dye Or en- Overfeed, Type of crimp (percent Denier tation percent absorbed in Ten., Elong., Mi, per angle 10 min. at g p.d. percent g.p.d. filament (deg) 140 F.) (d.p.f.)

Feed yarn 0. 42 6.0 36 29 15.8 13. 0 22 1. 08 5. 4 55 20 16. 4 19. 0 40 g 1. 46 4. 9 80 11 19.1 21. 0 100 Highly crimped--- 1. 43 5. 0 98 8. 5 19. 7 20.8

EXAMPLE V the separated filaments in the stream to shrink the fila- Filament yarn (70-denier, -filament, zero-twist, Y cross section) of poly(ethylene terephthalate) modified with 2.0% of a sulfonated derivative of isophthalic acid to provide dyeability with basic (cationic) dyes, was fed to a steam jet at 393 y.p.m. with an overfeed of 40% through a jet similar to FIGURE 1 of US. Patent No. 3,005,251 issued Oct. 24, 1961, to Hallden and Murenbeeld. The steam supply to the jet was superheated to a temperature of 460 F. at a pressure of 71 p.s.i. The yarn was wound up at a speed of 280 y.p.m. The treated yarn picked up more than twice as much basic dye as the untreated yarn when dyed with Du Pont Sevron Blue 56. The treated yarn, in fact, had 105% improvement in dye rate over the untreated yarn. There was no crimp in the jet processed yarn, but the individual filaments possessed random S and Z twist throughout their length. This improvement in dye rate achieved with the treated yarn is not specific to the conditions used in this given dyeing procedure. Numerous other basic dyes had equivalent improvement including Du Pont Brilliant Green Crystals, Du Pont Fuchsine, and Sevron Blue BGL. Similar improvements in dyeability have been achieved with fabrics prepared from the yarns using bath to fabric ratios as low as 15:1 and as high as 500:1.

EXAMPLE VI A single end of poly(epsilon-caproamide) yarn was bulked in the jet of FIGURE 1. The yarn was 4200-denier, 224-filament, zero-twist bright yarn with round filament cross section. The yarn was passed through the jet with feed speed of 200 yards per minute, steam temperature 530 F., and 44% overfeed. An unbulked yarn was obments at least 12% and increase the rate of dyeability at least withdrawing the strand from the stream at a lower rate than said feed rate which provides at most 40% overfeed to the stream, the overfeed being adjusted to provide for said shrinkage without curvilinear crimping of the filaments, and collecting the treated strand.

2. A process as defined in claim 1 wherein said overfeed is from 12% to 30%.

3. A process as defined in claim 1 wherein said compressible fluid is steam at 400 to 600 F.

4. A process as defined in claim 1 wherein the strand is withdrawn from the fluid stream within a sufiiciently short time to provide a filament tenacity in excess of 0.8 T (D /D where T is the filament tenacity before treatment, and D and D are the dyeability rates of the filament before and after treatment.

References Cited UNITED STATES PATENTS 2,379,824 7/1945 Mummery 28-72 2,435,891 2/1948 Lodge 57-34 3,380,242 4/1968 Richmond et a1. 28-1 FOREIGN PATENTS 161,076 2/1955 Australia.

MERVIN STEIN, Primary Examiner.

Us. 01. X.R. s7 140, 157

Patent Citations
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US2379824 *Mar 6, 1943Jul 3, 1945Du PontProcess and apparatus for treating artificial filaments
US2435891 *Jun 24, 1941Feb 10, 1948American Viscose CorpMethod and apparatus for crimping textile fibrous material
US3380242 *Feb 11, 1958Apr 30, 1968American Enka CorpYarn and method of making same
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3748844 *Aug 4, 1971Jul 31, 1973Du PontPolyester yarn
US4261084 *Jan 29, 1979Apr 14, 1981Neumuenstersche Maschinen Und Apparatebau Gesellschaft Mbh.Device for crimping synthetic plastic fibers
US4453298 *Apr 22, 1981Jun 12, 1984Rieter Machine Works, Ltd.Construction of thread texturizing nozzles
US5212858 *Jun 11, 1991May 25, 1993Asten Group, Inc.Apparatus for capturing and stabilizing a yarn
U.S. Classification28/271, 48/197.00R, 57/350, 264/289.6, 28/272, 57/246, 28/273, 57/248, 57/205
International ClassificationD02G1/16
Cooperative ClassificationD02G1/168
European ClassificationD02G1/16G