IL46235A - Process for preparing a package suitable for dyeing of textured yarn - Google Patents

Abstract

A textured yarn is tensioned sufficiently to stabilize the yarn but insufficiently to remove the texture and is wound at a low tension to form a soft package on a collapsible package support. The yarn package is then dyed at an elevated temperature. [US3892020A]

Description

e&feaar-tmw&a ny*a*V navaium n*«ati i*V«n A process for preparing a package suitable or dyeing of iextarea ym E. I· £0 PGHT DE ΒΕ!0ϋΒ8 ASD CQEiPABY The present invention relates to a process of preparing a soft package, for dyeing, of a relatively inelastic textured continuous multifilament or spun synthetic polymeric yarn which shrinks substantially under the heating conditions encountered following texturing.

A process for texturing continuous filament yarn or staple yarn by means of a turbulent air jet is known from Breen, U.S. Patent No. 2,852,906. In the case of continuous multifilament yarn, the turbulent jet forms each filament occasionally into a loop and entangles the filaments to bind the loops into a yarn structure consisting of a more or less compact entangled core, crunodal filament loops extending out from the surface of the core and some filament loops being buried within the core structure. The yarn is fed into the texturing jet at a rate greater than the take-away speed to provide the excess filament length required for forming loops and a high degree of entanglement.

After the textured yarn is taken away from the jet at low tension, it must be stretched to stabilize the structure. Otherwise, the yarn will stretch when it is woven or knitted at tensions higher than exist in the jet portion of the texturing process and will usually do so nonuniformly because of nonuniform cyclical tensions in weaving and knitting operations, resulting in irregular fabric appearance. Therefore, it is necessary to apply a tension to the yarn greater than that which the yarn will receive in subsequent winding and fabric making operations. Normally, this is done by winding the yarn on a package at sufficient tension to stabilize the yarn and to provide a firm or hard package of minimum volume which can be handled and shipped without damage However, such hard packages are not suitable for package dyeing because they are so tightly wound that it is difficult for liquid dye to uniformly penetrate the package. A soft package of yarn, on the other hand, is easily penetrated with liquid dye and is desired for package dyeing of yarn. This has normally been accomplished in the past by rewinding the yarn onto a collapsible core under low winding tension to form a soft package. This additional step of rewinding is costly and time consuming.

The soft yarn packages are placed in a dye bath and dyed. They are normally stacked in axial alignment on a dye tank loading rod and compressed axially to eliminate spaces between the ends of adjacent yarn packages. Dye is then circulated through the dye tank loading rods which are normally perforated tubes of smaller diameter than the inside diameter of the yarn packages and the dye temperature is raised at a controlled rate. In a typical dye heat cycle for a yarn which has previously been autoclaved, the bath is heated from 60 to 110 °C. at a rate of 4 degrees C. per minute and from 110 to 130°C. at a rate of 2 degrees C. per minute. The critical dyeing temperature for such yarn is 110 to 130 °C.

After dyeing, the yarn is rewound onto a cone to provide a finished package of textured and dyed yarn. During winding, the yarn is lubricated to improve its knitting properties.

It has now been found that yarn may be air textured and stabilized for uniform dyeing by a process of this invention. According to the present invention, there is provided a process for preparing a soft package suitable for package dyeing of uncrimped, bulked, air textured yarn having texture —giving crunodal loops characterized by leading yarn directly from a jet that produces said yarn to a stretching step wherein stretching is to a degree sufficient to stabilize the yarn but insufficient to eliminate texture-giving loops, followed by winding the so stretched yarn at a tension of less than about 0.04 gram per denier onto a core and forming a package having a Shore hardness of less than 40 degrees. Stabilization of yarn referred to is the process of stretching whereby entangled loops encircle and tighten around the nodes of other entangled loops to provide greater stability against unlooping, as explained in detail in U.S. Patent No. 2,852,906, Column 4, beginning at line 47. Shore hardness is a measure of package density and was determined by pressing a spring-loaded puncher against the surface of the material to be measured and the amount of indentation is registered in terms of degrees Shore hardness the instrument used was a 2-1/2 mm diameter ball-point puncher made by Zwick and Co., Einzingen, near Ulm, Germany, called a Package Density Measuring Instrument; measurements were made on the left shoulder, middle, and right shoulder of each package and the three readings were averaged; for further details, see ASTM Spec. 2240, and Bulletin R-8 by Shore Instrument and Manufacturing Co., Jamaica, New York, U.S.A. Crunodal loops are the kind of loops produced in an air jet texturing process, e.g., as in U.S. Patent Nos .2 , 783, 609 (Breen) and 3,545,057 (Lubach) .

Thereafter, the package of yarn may be dyed at elevated temperature to shrink the yarn and dye it simulta neously. The stretching is preferably under a tension higher than the tension which the finished yarn receives in subsequent rewinding, knitting or weaving operations and is preferably by an amount of 5-20%. The stretching may advantageously be per formed by leading the yarn from the smaller step of a stepped roll which controls the take-away speed of the yarn from the texturing jet to a larger step of a diameter greater by 5 to 20% than the smaller step, by the use of guides or freely rotating separator rolls. The degree of stretch, however, must usually be less than the degree of overfeed through the texturing jet, in order to retain a substantial degree of loops . When the feed yarn to the texturing operation is fully drawn, the overfeed minus the stretch is preferably at least 10% but is dependent on the material used or the degree of texture desired. When undrawn or partially drawn feed yarn is used, the degree of stretch may exceed the overfeed while retaining bulk-giving loops.

The process of this invention significantly reduces the steps required in texturing and dyeing yarn, and therefore reduces cost. Waste losses also decline. The use of a stepped roll for stretching the yarn prior to winding a soft package permits use of texturing machines having only one powered drive between texturing and windup.

Figure 1 is a schematic view of suitable equipment for processing yarn into packages according to the invention.

Figure 2 is a sectional view of a preferred texturing jet.

Figure 3 is a view of a yarn dyeing apparatus suitable for use with packages prepared by the process of the invention.

Figure 4 is a perspective view of a dye loading rod of Figure 3.

Figure 5 is an end view of the dye loading rod of Figure 4.

Referring to Pig. 1, yam 4 is taken from feed yarn package 2 mounted on platform 3 and passes through tension and stop motion device 5 to feed roll 6 where it may be wrapped several times with the aid of guide 7 to prevent slippage. It then passes to texturing Jet 10 which is supplied with compressed air through pipe 8 from a source not shown. Optionally, the yarn may pass through a tank 9 where water or other treating liquid is applied to the yarn before entering texturing jet 10. It may be preferable to place an enclosure around bath 9 and jet 10 to collect droplets of liquid which escape from or are blown off the yarn. The textured yarn then contacts driven roll surface 24 operating at surface speed less than that of feed roll 6.

The yarn then passes to another roll surface 25 operating at a surface speed faster than roll surface 24. Roll surfaces 24 and 25 may be the smaller and larger diameter steps on a single driven stepped roll 17. Multiple wraps to reduce slippage may be provided by grooved guides 15 and 16 or equivalent means . The yarn then passes over one or more guides 18 to traverse guide 19 which winds the yarn as soft package 21 on core 20, which is preferably a commercially-available dye spring, collapsible both axially and radially. Core 20 is mounted on a chuck (not shown) which holds core 20 at or near its maximum diameter while package 21 is being wound. Yarn is wound at a tension considerably lower than that encountered during the stretching operation following texturing.

Fig. 2 shows details of a preferred texturing device Texturing jet 10 may preferably be a device of Lubach, U.S. Patent No. 3, * 0 7 in which compressed air flowing into the device through pipe 8 encounters a severe restriction such as hole 13 which directs a concentrated stream of high velocity fluid onto yarn 4 as it emerges from yarn guiding outlet 11. The turbulent air and the yarn then pass together through the throat of venturi 12. It may also be preferable to employ floating baffle plate 14 which is described in more detail in U.S. Patent Specification No. 3,835,510. Baffle 14 is free to pivot about hinge pin 23 which is supported by bracket 22 which may be clamped around the periphery of texturing jet 10 and may be adjustable along the length of the jet. Textured yarn leaves jet device 10 at approximately right, angles to its direction of travel through the jet. Use of this preferred texturing device not only allows satisfactory texturing at higher speed than prior devices but produces unusually uniform tension in the yarn between the texturing jet 10 and roll 17 which in turn allows more uniform stretching before winding.

Fig. 3 shows equipment suitable for dyeing the soft ' packages. Yarn packages indicated by 27 and 28 are stacked axially on dye loading rod 29 shown in greater detail in Figs. 4 and 5. The stack of packages is then compressed axially so that the ends of the dye springs compress axially and allo the edges of adjacent packages to contact each other so as to form a uniform column of softly packed yarn.

The rods are in a conventional yarn dye tank 26. The lid of dye tank 26 is then closed and dye is pumped from reservoir 30 through conduit 31. Pump 32 forces dye from reservoir 30 through conduits 31 and 33 into dye tank 26, and thence into conduit 34 having vertical pipes which connect with the center of packages 27 and 28. Dye is usually at some elevated temperature such as 60°C. when it is first introduced into the dye tank 26. Thereafter hot water or steam is introduced through conduit 36 from a reservoir (not shown), is circulated through heating coil 35 and is removed through conduit 37.

As the temperature rises, the yarn shrinks and the dye spring collapses radially to maintain a soft package of relatively uniform density having sufficient porosity to allow easy and uniform flow of dye through the package.

Figs . 4 and 5 show a preferred dye loading rod in greater detail. Conventional dye equipment generally employs a perforated tube having an outer diameter slightly smaller than the minimum inner diameter of a fully shrunk yarn package. When yarn packages of unshrunk yarn having a substantially larger internal diameter than the outside diameter of the dye rod are stacked on such a rod, the packages may be misaligned with each other by an amount equal to the difference between the inner diameter of the unshrunk package and the outer diameter of the dye rod. Such misalignment causes uneven compression of yarn at both the inside and outside of packages and results in uneven dyeing. The preferred rod of Figs. 4 and 5 consists of a longitudinally extending main member 38 having a cross section in the shape of a cross intersecting at 90° angles and having arms of equal length. The point of intersection 39 is the longitudinal axis of the rod. Dependent from member 38 are at least two longitudinally extending members 40 and l that are shown in the shape of a round bar supported on springs 2 which extend in a radial direction from the longitudinal axis 39 of the rod. When the springs are in expanded position holding rods 40 and 4l at full extension, the distance between the longitudinal axis 39 of the main member and the outermost point of either rod 40 or 41 at full extension, the distance between the longitudinal axis 39 of the main member and the outermost point of either rod 40 or 4l indicated as in the drawings is chosen to coincide with the inside radius of the collapsible core in its initial uncollapsed state. This ensures proper axial alignment of the packages. As the yarn shrinks radially, springs 2 compress. The lengths of the arms of the main members indicated by in the drawing should be slightly smaller than the inside radius of a core after full shrinkage.

The use of the terms "hard pack." and "soft pack" and their derivatives are of course relative. As stated before, a hard packed core of yarn is so tightly wound that it is difficult or impractical to penetrate with a liquid dye uniformly. A soft package of yarn, on the other hand, is easily penetrated with liquid dye uniformly. In general, a Shore hardness less than 40° is considered a soft package and a Shore hardness over 40° is considered a hard package.

Since the relative humidity of the room in which winding is performed affects the tension of the yarn as wound on the package, it is important to control the relative humidity of such room within a range of about + 5$ RH. That is to say, the relative humidity should not vary by more than this amount from time to time during the winding operations, and no winding machine should differ from any other running at the same operating conditions by more than this amount.

Although the following example concerns polyester yarn, similar conditions may be employed for texturing nylon, polypropylene or other yarns of commercial importance. In general, yarns having higher shrinkage during heating should be wound on core 20 at lower tensions. Whereas, a single end of 150 denier yarn is exemplified, multiple ends of the same or different yarns may be fed at the same or different speeds to the texturing Jet.

EXAMPLE Dacron® polyester yarn of 150 denier (I67 d-tex) having 68 filaments designated as R-10, Type 56, is placed on a device of Fig. 1 in which feed roll 6 is ojjerating at 482 yards per minute (440 meters per minute). The yarn passes through water bath 9 into texturing jet 10 shown in Pig. 2 in which hole 13 is 2.78 millimeters, yarn hole 11 is O.51 millimeters and venturi 12 is I.78 millimeters diameter. Air pressure is ll8 lbs./sq. in. gauge (8 atmospheres).

Baffle plate 14 is approximately 68 millimeters from hinge point 23 to the end and is 40 millimeters wide. Yam passes from the jet at low uniform tension to a smaller diameter step of roll 17 which is operating at 34θ yards/ in. (311 meters/ min.) with a resultant overfeed between feed roll 6 and roll surface 24 of 42$. Roll surface 25 is operating at 398 yards per minute (3G4 meters per min.) thus stretching the yarn between roll surfaces 24 and 25 by l4.5#. Therefore, the stretch which the yarn receives on the stepped roll is considerably less than the initial degree of overfeed, and the stretching serves mainly to stabilize the yam without destroying its bulk and texture. The yarn is wrapped around guide 15 and passes to the larger diameter step of roll 17. The yarn is then wound on the larger step with the aid of guide 16 and passes over to guide rods l8 to traverse 19 where the yarn is wound at a tension of 4 to 5 grams on dye spring 20 which is collapsible both radially and axially.

The finished yarn package has a Shore hardness of 24 + 2° with a density of 240 grams per liter. The denier of the yarn as wound on the package is approximately l80 (200 d-tex). Yarn packages are then stacked axially in a dye device and are exposed to liquid dye which is heated from 60 to 110°C. at a rate of 1°C. per minute and from 110 to 130°C. at a rate of 2°C. per minute. The optimum range for dye pickup for this yarn is 60 to 110° C. The denier of the yarn after dyeing is about 200 (220 d-tex). The yarn shrinks about 11$ during this process. The dye is held at 130° for at least 30 minutes, then the dye is pumped out of tank 26, the yarn packages are removed from dye rods 28 and are rinsed. Subsequently, the yarn is rewound onto cones and lubricated for knitting or weaving into fabrics. Waste loss during the present process is approximately 2% compared to approximately 10$ for the process of the prior art.

Claims (2)

CLAIMS:

1. A process for preparing a soft package suitable for package dyeing of uncrimped, bulked, air textured yarn having texture-giving crunodal loops characterized by leading yarn directly from a jet that produces said yarn to a stretching step wherein stretching is to a degree sufficient to stabilize the yarn but insufficient to eliminate texture-giving loops, followed by winding the so stretched yarn at a tension of less than about 0.04 gram per denier onto a core and forming a package having a Shore hardness of less than 40 degrees.

2. A process according to Claim 1 wherein the core is radially and axially collapsible and the package is dyed at 60 to 130°C.