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Publication numberUS3791130 A
Publication typeGrant
Publication dateFeb 12, 1974
Filing dateOct 28, 1971
Priority dateNov 4, 1970
Also published asCA952385A1, DE2154887A1
Publication numberUS 3791130 A, US 3791130A, US-A-3791130, US3791130 A, US3791130A
InventorsChiba Y, Inuyama H, Tomioka S
Original AssigneeToray Industries
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for false-twisting a synthetic filament yarn
US 3791130 A
Abstract
In the method, the yarn is heated at a temperature at which the yarn is plasticized. The yarn is then passed through a closed path formed around a pin while contacting the periphery of the pin. A portion of the yarn emerging from the closed path is brought into contact with a portion of the yarn entering the closed path. The entering and the emerging portions of the yarn are entwined with each other at entry and exit regions of the closed path in such a manner that each portion of the yarn goes around the other in at least one turn under friction while travelling in the same direction.
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United States Patent [191 Inuyama et al.

[451 Feb. 12, 1974 METHOD FOR FALSE-TWISTING A SYNTHETIC FILAMENT YARN [75] Inventors: IIisao Inuyama, Otsu; Sadao Tomioka, Kusatsu; Yoshihiko Chiba, Kyoto, all of Japan [30] Foreign Application Priority Data 3,035,396 5/1962 Biggers 57/157 MS 3,148,520 9/1964 Biggers..... 57/157 MS 3,178,795 4/1965 Warthen 57/157 MS FOREIGN PATENTS OR APPLICATIONS 227,591 4/1960 Australia 57/157 TS Primary Examiner-John Petrakes Attorney, Agent, or FirmAllan Ratner ABSTRACT In the method, the yarn is heated at a temperature at which the yarn is pla'sticized. The yarn is then passed through a closed path formed around a pin while contacting the periphery of the pin. A portion of the yarn emerging from the closed path is brought into contact with a portion of the yarn entering the closed path. The entering and the emerging portions of the yarn are entwined with each other at entry and exit regions of the closed path in such a manner that each portion of the yarn goes around the other in at least one turn under friction while travelling in the same direction.

7 Claims, 14 Drawing Figures PATENTEB FEB 1 2 I974 SHE! 3 0F 5 PATENTEHFEB 12 m4 SHEEI II [If 5 6'0 9'0 ""CROSS ANGLE (sf) (DEGREE) ZOOO- F/QS METHOD FOR FALSE-TWISTING A SYNTHETIC FILAMENT YARN The present invention relates to a method and apparatus for false-twisting a synthetic filament yarn, more particularly, relates to a method and apparatus for false-twisting a thermoplastic synthetic monoor multifilament yarn so as to result in a textured yarn having a high torque and little or no crimp.

In the conventional method, the synthetic filament yarn is false-twisted by using a spindle and there is an upper limit to the rotation number of the spindle, hence, there is an upper limit to the velocity of processing of the false-twisting. Particularly, there is the disadvantages that the productivity of the textured yarn from fine denier filament yarn is relatively low.

The conventional friction drive method for falsetwisting the filament yarn can be carried out with a high productivity at a large twist number. However, this method has the disadvantages that the friction member used for false-twisting the filament yarn must be made of a special hard material having a high resistance against rubbing and that it is very difficult to control the twist number for the filament yarn because the frictional property of the frictional member varies owing to transfer of the oiling agent applied to the filament yarn to the friction surface thereof.

Further, the textured yarns produced by the abovementioned conventional false-twisting method have a high bulkiness due to the highly crimped filaments, but the torque is relatively low.

There is also a prior art wherein a filament yarn passing across a wire or filament yarn which is itself travelling longitudinally, makes contact with the wire or filament yarn at one point under friction. The filament yarn is false-twisted by the forward travel of the wire or filament yarn, and the resultant textured yarn has a high bulkiness due to the crimp of the filaments. However, it is known that the above method cannot produce textured yarn having a high torque.

As stated above, the conventional false-twisting method can produce a textured filament yarn having a high crimp and bulkiness but can not provide a textured yarn having a high torque and little or no crimp. Such textured yarn having a high torque and little or no crimpis suitable for knitted articles, especially, hosiery, and more especially, stockings. The knitted articles high stretchability, a beautiful appearance and an elegant hand feeling. For the above-stated advantages, the high torque textured filament yarns have been recently spot-lighted and demand for them increases.

An object of the present invention is to provide a method and apparatus for false-twisting a synthetic filament yarn into a textured yarn having a high torque and which are substantially no crimp.

Another object of the present invention is to provide a method and apparatus for false-twisting a synthetic filament yarn at a high processing velocity into a textured yarn having a high torque.

A further object of the present invention is to provide produced from the high torque textured yarn have a a method and apparatus for false-twisting a synthetic vention. The method of the' present invention includes the step of heating a synthetic monoor multi-filament yarn at a temperature at which the yarn is plasticized by passing the yarn through the heating means, and the step of false-twisting the yarn by passing the yarn through a closed path formed around a pin, the yarn enters into and emerges from the closed path while contacting the periphery of the pin, and, at entry and exit regions of the closed path, a portion of the yarn entering into the closed path and a portion of the yarn emerging from the closed path are entwined with each other in at least one turn under friction while travelling in the same direction, whereby the entering portion of the yarn is twisted by the forward travel of the emerging portion and a portion of the yarn emerged from the closed path is untwisted by the forward travel of the entering portion.

In the above method, since the yarn is entered into and emerged from the closed path while keeping contact with the periphery of the pin, the twine portion is secured between points of contact at which the portions of the yarn entered into and emerging from the closed path are in contact with the periphery of the pin. This is an advantageous feature of the method of the present invention because this results in a uniform processing of the false-twisting.

The apparatus of the present invention comprises a feed means for a monoor multi-filament yarn, heating means for the yarn disposed downstream of the feed means, means for defining a closed path for the yarn disposed downstream of the heating means and containing at least one pin on the periphery ofwhich a portion of the yarn entering into the closed path and a por tion of the yarn emerging from the closed path are entwined with each other in at least one turn, and delivery means for the yarn disposed downstream of the closed path-defining means.

ln order to produce the textured filament yarn having a high torque and little or no crimp, it is necessary to satisfy the following condition:

1. The filament yarn is uniformly false-twisted under a predetermined condition.

2. The false-twisted filament yarn is sufficiently heatset at the twisted form and thereafter, untwisted.

3. in the false-twisting process, the filament yarn is deformed at a high torsion and low flexure.

in the case where two filament yarns travelling through paths different from each other and intersecting each other, are false-twisted each by the forward travel of the other filament, the twist number of the resultant false-twisted yarn depends on the travelling velocity of the yarns, intersecting angle between the yarns, filament number in the yarns, and diameter and frictional efficiency of the yarn.

The above-mentioned relationship is summarized in the following equation (l):

T B' VSinO/rrdl/V B" Sin0/1rd(l a) wherein T represents the twist number in turns/m, V the velocity in m/min of yarn emerging from the entwining region, V the velocity in m/min of the yarn entering into the entwining region, a the diameter in mm of the yarn, B the frictional coefficiency of the yarn, 0 the twine angle between the entering portion and the emerging portion of the yarn, and a the shrinkage of the yarn due to twist of the yarn which is equal to V V V.

The twine angle 6 of the yarn used herein means an angle between the axis lines of each of the yarns entwined with each other, The frictional coefficient [3 is a variable which varies with the frictional coefficient, contact area and contact pressure of the yarns entwined with each other. That is, the diameter, filament number and frictional coefficient of the yarns depend on the kind of the filament yarns used, hence, in the case where preselected filament yarns are false-twisted at a predetermined velocity, the twist number can be adjusted by controlling the twine angle and contact area and pressure between the yarns twined with each other. The contact pressure of the yarns can be adjusted by controlling the tension on the filament yarns.

Also, the twine angle is adjusted by controlling the cross angle between the portion of the yarn just entered into the closed path and the portion of the yarn just emerged from the closed path. Accordingly, the twist number can be adjusted by controlling the cross angle as defined above and the tension of the yarns. The method of controlling the cross angle will be illustrated in detail hereinafter.

In the method of the present invention, the filament yarn to be false-twisted is heated at a temperature at which the yarn is plasticized and then passed through a closed path, and at entry and exit region of the closed path, the entering portion and the emerging portion of the yarn are entwined with each other in at least one turn under friction. Such heating and entwining results in the following advantages.

1. In the conventional method as stated above, the entering and emerging portions of the yarn intersect each other so as to make contact substantially at one point. Compared with this, in the method of the present invention, the entering and emerging portions of the yarn are entwined with each other so as to make contact over a certain length. Therefore, it is obvious that the frictional efficiency [3 in the method of the present invention is higher than that of the conventional method. Such high frictional efficiency derived from the method of the present invention results in a twist number greater than that of the conventional method.

2. The entering and emerging portions of the yarn are pressed to each other at the region in which they are twined with each other so as to enhance the frictional efficiency [3, and hence, to increase the twist number.

3. The pressure on the portions of the yarn in the twine region of the closed path causes a decrease of bending of the yarn in the twisting process. Therefore, in the false-twisting process according to the present invention, the filament yarn is highly twisted and slightly bent, and the filaments in the yarn slightly migrate owing to the pressure. Such slight bending of the yarn and migration of the filaments in the false-twisting process is very effective for preventing the yarn from crimping. Also, the high twist of the yarn results in an enhanced torque of the yarn.

4. According to the method of the present invention, the portion of yarn travelling toward the closed path is heated by the heater located upstream of the closed path at a temperature at which the yarn is plasticized and then cooled between the heater and the closed path while being twisted by the forward travel of the portion of the yarn emerging from the closed path. Accordingly, the portion of the yarn travelling toward the closed path is heat-set in the twisted form at a region upstream of the closed path. Next, the twisted and heat-set portion of the yarn enters into the closed path and is untwisted in the entry region of the closed path by the forward travel of the emerging portion of the yarn. However, this untwist is very slight since the entered portion of the yarn makes contact briefly with the periphery of the pin, and advances along the periphery of the pin in the twisted form. When the twisted portion of the yarn reaches the exit region of the closed path, the twisted portion is further-twisted very slightly by the forward travel of the entering portion of the yarn. Then, when the twisted yarn emerges from the closed path, the emerging portion of the yarn is completely untwisted by the forward travel of the entering portion of the yarn. Accordingly, the yarn passes through the closed path in the twisted form under tension. This passing of the twisted yarn under tension is effective for enhancing the torque of the yarn and for lowering the crimp of the yarn.

In the conventional false-twisting process, in order to produce textured yarn having a high crimp and a high bulkiness, the filament in the yarn is certainly migrated and bent outwardly so as to increase the diameter of the yarn. Compared with this, in the false-twisting according to the present invention, the filament in the yarn is prevented from migration and bending so as not to increase the diameter of the yarn. This results in the high torque and low crimp of the textured yarn obtained from the method of the present invention.

Textured yarn having an optimum torque can be prepared by false-twisting at an optimum twist number which depends on the total denier of the yarn and number of filaments in the yarn. That is, if the twist number is excessively large the resultant textured yarn has undesired crimp, and if the twist number is excessively low, the resultant textured yarn has a non-uniform torque. For example, six kinds of nylon 66 filament yarns having filament counts of 17 denier/3 filaments, 20 denier/2 filaments, 2O denier/3 filaments, 22 denier/3 filaments, 25 denier/3 filaments and 25 denier/5 filaments, were false-twisted by the method of the present invention at various twist numbers, and crimping property of the resultant textured yarns and evenness of knitted fabric from the resultant textured yarns were observed.

The results of the observations are shown in Table l Filament count Item 17 DH F 20 D/2 F 20 D/3 F 22 0/3 F 25 D/3 F 25 D/S F Twist number at 2300 2500 2100 2000 I900 1600 which crimp is created Twist number at 2000 2300 1900 I800 I700 1300 which uneven fabric results Optimum twist 2170 2450 2000 I910 I790 I390 number The optimum twist nu nibers mentioned above were obtained emprically for the above experimentation. The twist number at which uneven fabric results varies depending on the structure of the fabric and tension during fabric-producing process. Therefore, the twist numbers at which uneven fabric results as shown in Table 1 are not always the lower limit of the twist number for the variously yarns in the method of the present invention. Sometimes, a twist number which is lower than the twist number at which uneven fabric results as shown in Table 1, results in a uniform fabric.

From the above-stated experiment, in order to obtain a textured multi-filament yarn having an optimum torque, it is preferable that the multi-filament yarn is twisted at a twist number satisfying the following relationship (II):

1 wherein T represents the twist number in turn/meter, D

the denier of the yarn and f the numbers of filaments in the yarn and f a 2.

The optimum twist number for the filament yarn is selected in consideration of the use of the resultant textured yarn. If it is desired that the textured yarn has a very high torque, the filament yarn is false-twisted at the upper limit of the twist number satisfying the relationahip (11). However, if it is desired that the textured yarn has a relatively low torque, the filament yarn is false-twisted at a relatively low twist number satisfying the relationship (11).

In consideration of processing efficiency, tension and temperature which vary during the false-twisting process, it is more preferable that the yarn is twisted at the twist number satisfying the following relationship (Ill).

15480/ V D'fX 0.40 T 15480/ VDfX 0.95

In the case where the yarn is composed of a monofilament, even when the twist number is larger than 15480] V Of, the resultant textured yarn has no crimp.

The present invention provides a method and device for adjusting the cross angle between a portion of the yarn just entered into the closed path and a portion of the yarn just emerged from the closed pass in order to control the twist number of the yarn.

The method and apparatus of the present invention will be explained in detail by the following illustration and the accompanying drawings in which;

FIG. 1 is aschematic view of an embodiment of the apparatus of the present invention,

FIGS. 2A and 2B are schematic views showing the relationship between the direction of entwining of yarns and the direction of twisting of the yarns,

FIG. 3 is a schematic view ofanother embodiment of the apparatus of the present invention,

FIGS. 4A, 4B and 4C are all schematic views showing the relationship between the position of a rotatable roller in the closed path the cross angle d) between a por- 6 tion of yarn just entered into the closed path and a portion of yarn just emerged from the closed path in the apparatus of FIG. 3,

FIGS. 5A and 5B are both schematic views showing the relationship between the diameter of the fixed pin and the cross angle :12 in the apparatus of FIG. 1,

FIG. 6 is a schematic view showing the relationship between the position of the fixed pin and the cross angle (1:,

FIG. 7 is a graph showing the relationship between the cross angle (1) and twist number,

FIG. 8 is a graph showing the relationship between the diameter of the fixed pin and twist number,

FIG. 9 is a graph showing the relationship between the denier of the filament yarn and twist number,

FIG. 10 is a schematic view showing a conventional false-twisting method other than the method of the present invention.

Referring to FIG. 1, a filament yarn 2 is fed by means of a pair of feed rollers 4 from a feed package 1 onto the heater 5 through a guide 3. The yarn 2 is heated by the heater 5 to a temperature at which the yarn 2 is plasticized, cooled downstream of the heater 5 and then wound on the periphery of a fixed pin 6 in at least one turn so as to form a closed path 12 around the fixed pin 6. At an entry and exit region 7 of the closed path 12, a portion of the yarn 2 entering into the clpsed path and a portion of the yarn 2 emerging from the closed path are entwined with each other in at least one turn. The portion of the yarn 2 emerged from the closed path 12 is delivered by a pair of delivery rollers 8 and then wound up by means ofa driving roller 10 into a take-up package 11 through a guide 9.

Referring to FIGS. 2A and 2B, the yarn 2 travels through a closed path 12 formed around the periphery of the fixed pin 6. At the entry and exit region 7, a portion 13 of the yarn 2 entering into the closed path 12 and a portion 14 of the yarn 2 emerging from the closed path 12 are entwined with each other. In FIG. 2A, the portion 13 of the yarn 2 is entwined about the portion 14 of the yarn 2 in the S direction, and twisted in the S direction by the forward travel of the portion 14. As shown in FIG. 1, since the heater 5 is disposed upstream of the closed path 12, the yarn twisted in the S direction is heat-set by the heater 5, and cooled between the heater 5 and the pin 6. When the twisted and heat-set portion of the yarn 2 advances into the closed path 12, the portion 16 of the yarn 2 is slightly untwisted in the Z direction by the forward travel of the emerging portion 14 because the entered portion 16 of the yarn 2 immediately contacts the periphery of the fixed pin 6 so as to prevent untwisting of the portion 16. In other words, owing to the contact of the portion 16 with the periphery of the fixed pin 6, the S twists of the yarn 2 are retained during the advance along the periphery of the fixed pin 6. When the S twisted portion of the yarn 2 approaches the exit region of the closed path 12, the emerging portion 14 of the yarn 2 is slightly further twisted in S direction by the forward travel of the entering portion 13 of the yarn 2 because the emerging portion 14 contacts the periphery of the fixed pin 6. Thereafter, the yarn 2 passes through the region 7 of the closed path 12 wherein the entering and emerging portions 13 and 14 of the yarn are entwined with each other in at least one turn. The portion 17 of the yarn 2 emerged from the closed path 12 is entirely untwisted in the Z direction by the forward travel of the entering portion 13 of the yarn 2.

As stated above, the twisting of the emerging portion 13 and the untwisting of the entered portion 14 are very slightly carried out in the closed path 12, and thus, they are negligible.

Accordingly, in the false-twisting according to the method as shown in FIG. 2A, substantially, the portion 13 of the yarn 2 entering into the closed path 12 is twisted in the S direction and the portion 17 of the yarn 2 emerged from the closed path is entirely untwisted in the Z direction. The resultant textured yarn has a high torque in the Z direction.

In FIG. 2B, the entering portion 13 and the emerging portion 14 of the yarn 2 are entwined in the Z direction. Accordingly, the entering portion 13 is twisted in the Z direction by the forward travel of the emerging portion 14 and heat-set by the heater as shown in FIG. 1, and the emerged portion 17 is untwisted in the S direction by the forward travel of the entering portion 13. The resultant textured yarn from the method as shown in FIG. 28 has a high torque in the S direction. That is, according to the method of the present invention, the twist direction of the yarn can be easily established by selecting the entwining direction of the entering and emerging portions of the yarn 2.

As shown in FIGS. 2A and 2B, the entering portion 13 and the emerging portion of the yarn 2 are entwined with each other while in contact around the periphery of the fixed pin 6. The entwined portions of the yarn 2 are kept on or near the periphery of the fixed pin 6.

In order to keep the entwined portions of the yarn on or near the periphery and to avoid creation of excessive friction between the fixed pin periphery and the yarn, it is necessary that the diameter of the fixed pin is not too large. That is, generally, it is preferable that the diameter of the fixed pin is in a range from 0.8 to 3.0 mm. Also, it is necessary that the fixed pin periphery has a low frictional coefficient and a high resistance to rubbing. Accordingly, in general, the fixed pin is made of ruby, sapphire or alumina ceramic.

In the method and apparatus of the present invention, it is preferable that the pin for defining the closed path is fixed in a non-rotatable condition, but, sometimes, it is allowable for the pin to be rotatable.

Referring to FIG. 3, the closed path 12 is defined by the fixed pin 6 and a rotatable guide roller 15.

As stated hereinbefore, the twist number varies with variation of the cross angle between the emerged portion 17 and the entered portion 16 of the yarn 2, and when the cross angle is 90, the entering portion 13 is twisted at a maximum twist number.

In FIGS. 4A, 4B and 4C, the cross angle (1: can be varied by moving the rotatable guide roller along the direction of the arrows indicated in the drawings. That is, comparing FIG. 48 with FIG. 4A, when the guide roller 15 is approached to the emerged portion 17, the cross angle 4) is decreased so as to decrease the twist number.

As shown in FIG. 4C, when the guide roller 15 is approached to the fixed pin 6, the cross angle d: is decreased. Also, comparing FIG. 4A with FIG. 4C, an increase of the diameter of the guide roller 15 results in decrease of the cross angle (1).

Referring to FIGS. 5A and 5B, the fixed pin 60 shown in FIG. SA has a diameter smaller than that of the fixed pin 61) shown in FIG. 5B. This results in the fact that the cross angle (pa in FIG. 5A is larger than the cross angle (15b in FIG. 58. That is, the cross angle d) can also be varied by changing the diameter of the fixed pin.

Referring to FIG. 6, the cross angle (1) is varied by moving the fixed pin 6 along the direction of the arrow as shown in the drawing.

In FIG. 7, a curve (a) shows the relationship between the twist number and the cross angle 4) when a nylon 66 filament yarn of 20 denier/3 filaments was falsetwisted by entwining in one turn, utilizing the apparatus as shown in FIG. 3 wherein a rotatable guide roller of 15 mm diameter is arranged at a distance of 25 mm from a fixed sapphire pin of 2 mm diameter, at a feed rate of 700 m/min, under a tension of 0.3 g/d. The curve (b) shows the same relationship as that of the curve (a) except that the yarn is entwined in two turns. From the curves (a) and (b), it is clear that the closer the cross angle approaches the more the twist number increases.

FIG. 8 shows the relationship between the diameter of the fixed pin and the twist number when a nylon 6 filament yarn of 20 denier/3 filaments is false-twisted at a feed rate of 700 m/min under a tension of 0.3 g/d by utilizing the apparatus as shown in FIG. 1 using several fixed sapphire pins having diameters different from each other. As is clearly shown in FIG. 8, the greater the diameter of the fixed pin, the less the twist number.

FIG. 9 shows the relationship between the twist number, denier of yarn and number of filaments in the yarn when nylon 6 filament yarns of denier and numbers of filaments different from each other are false-twisted by means of an apparatus as shown in FIG. 3 using a fixed sapphire pin of 2 mm diameter, and a feed rate of 700 m/min under a tension of 0.2 g/d. From the drawing, it is clear that the greater the denier of the yarn and the greater the number of filaments in the yarn, the less the twist number of the textured yarn false-twisted according to the method and apparatus of the present invention.

When the textured yarn manufactured by the method and apparatus of the present invention is freely suspended, it rotates in a direction opposite to that of the false-twisting until it reaches a stationary condition or creates snarls, but substantially does not create crimp. Accordingly, the fabric from the textured yarn according to the present invention has a low bulkiness, high stretchability,- smooth appearance and elegant hand feeling.

The method and apparatus of the present invention does not require a rotor member rotating at a high velocity such as a spindle and frictional member. Hence, the apparatus of the present invention is very simple in its construction and can falst-twist the yarn at a very high velocity, for example, 500 to 2,000 m/min. It is accordingly possible to connect the false-twisting step of the present invention to the spinning and drawing step of the filament yarn so as to continuously carry out spinning, drawing and false-twisting steps. Also, the method and apparatus of the present invention can be carried out at a very low processing cost.

The examples which follow are given for the purpose of illustrating in detail the present invention.

Example 1 A nylon 66 filament yarn of 25 denier/3 filaments was false-twisted in the S direction and the Z direction by utilizing an apparatus as shown in FIGS. 1, 2A and 28 using a fixed sapphire pin of 0.8 mm diameter under the following conditions:

Tension on the yarn upstream to the pin: 5 g Tension on the yarn downstream from the pin: 24 g Feeding rate of the yarn: 300 m/min Heater temperature: 180C Heating time: 0.5 second Cross angle (it): 80 Twine number: I turn The yarn was false-twisted at a twist number of 2,300 turns/meter and converted to a textured yarn having a tenacity of 98 g, an elongation at break of 12 percent and a snarl index of 32.

The snarl index above represents the magnitude of the torque of the textured yarn and is determined in the following manner. A yarn is stressed between a fixed end support and a movable end support such that the length under a tension of 0.1 g/denier is 50 cm.

A weight of 50 mg is hung at the center of the yarn. The movable end support is moved toward the fixed end support. When the yarn is first snarls at atravel length of in X cm, the snarl index is determined from the equation:

Snarl Index (50 X) X 2 The resultant textured yarn had no crimp.

A stocking was knitted from the resultant textured yarns of S and Z torques by alternately feeding them. The resultant stocking had a high stretching property and a soft touch.

For comparison, the above false-twisting procedure was repeated except that the yarn was merely intersected at a point as shown in FIG. instead of entwining the yarn.

The resultant textured yarn had numerous crimps and no torque.

Example 2 Apolyetlyleneterephthalate filament yarn of 50 de- [tier/l2 filaments was false-twisted in the S and Z directions by means of apparatus the same as that used in Example 1 under the following conditions:

Tension on the yarn upstream to the pin: 6 g Tension on the yarn downstream from the pin: 30 g Feeding rate of the yarn: 250 m/min Heater temperature: 220C Heating time: 0.6 second Cross angle (4)): 85 Twine number: I turn Example 3 A nylon 6 mono-filament yarn of denier was false twisted in the S and Z directions by means of the apparatus the same as that used in Example 1 under the following conditions.

Tension on the yarn upstream of the pin: 4 g Tension on the yarn downstream from the pin: 20 g Feeding rate of the yarn: 500 m/min Heater temperature: 180C Heating time: 0.3 second Cross angle 5): 85 Twine number: 2 turns The mono-filament yarn was false-twisted at a twist number of 1,800 turns/meter and converted to a torque yarn having a tenacity of g, an elongation at break of 15 percent and a snarl index of 56. The resultant torque yarn had no crimp.

A stocking was prepared from the resultant S and Z torque yarns by alternately feeding them. The resultant stocking had a high stretching property and a uniform appearance.

Example 4 A nylon 6 mono-filament yarn of 20 denier having an original twist of 14 turns/meter in the S direction was false-twisted in the S direction by the apparatus as shown in FIG. 6 containing a rotatable pin of 15 mm diameter under the following conditions.

Tension on the yarn upstream of the pin: 4 g Tension on the yarn downstream from the pin: 25 g Feeding rate of the yarn: 500 m/min Heater temperature: l80C Heating time: 0.3 second Cross angle (4)): 60

Twine number: I turn The false-twisting was effected at a twist number of 2,100 turns/meter, and the yarn was converted to a torque yarn having a snarl index of 54.5 and no crimp.

For comparison, the above procedure was repeated except that the yarn was merely intersected in the manner shown in FIG. 10 instead of twining the yarn. The false-twisting was carried out at a twist number of 762 turns/meter and the yarn was converted to a crimped yarn having numerous crimps and no torque.

Example 5 Example 6 A nylon 6 filament yarn of 20 deniers/3 filaments was false-twisted in the S and Z directions by employing the apparatus shown in FIGS. 3, 4A and 48 comprising a fixed sapphire pin of 2 mm diameter and a rotatable guide roller of 15 mm diameter disposed at a distance of 2.5 cm from the pin center to the roller center under the following condition:

'I'cnniun on the yarn upstream of the pin: 4 g 'l'ension on the yarn downstream from the pin: l4 g Feeding rate of the yarn: 700 m/min Temperature of heater: Distributed in 2l0-l9U-l80C Time of heating: 0.] second Cross angle ()I 50 Twine number: 1 turn The yarn was false-twisted at a twist number of 1,500

turns/meter and converted to a torque yarn having a tenacity of 82 g, a snarl index of 43 and no crimp.

The resultant S and Z torque yarns were used for the manufacture of a stocking by alternately feeding them. The resultant stocking had a high stretching property and uniformity and elegant hand feeling.

For comparison, the above procedure was repeated except that the yarn was merely intersected on the periphery of the fixed pin instead of entwining the yarn. The yarn was converted to a textured yarn having numerous crimps and no torque.

What we claim is:

l. A method of producing a high torque filament yarn comprising the steps of heating a thermoplastic synthetic mono or multifilament yarn at a temperature at which said yarn is plasticized;

passing said yarn through a closed path formed around a pin while contacting the periphery of said pin, and;

bringing a portion of said yarn emerging from said closed path into contact with a portion of said yarn entering into said closed path,

said entering and emerging portions of said yarn being entwined with each other at entry and exit regions of said closed path in such a manner that each portion of said yarn goes around the other in at least one turn under friction while travelling in the same direction.

2. A method as claimed in claim 1, wherein said closed path is formed around a fixed pin.

3. A method as claimed in claim 1, wherein said closed path is formed around a rotatable pin.

4. A method as claimed in claim 1, wherein said closed path is formed around a fixed pin and a rotatable guide roller disposed apart from said fixed pin.

5. A method as claimed in claim 1, wherein the number of false-twists in turn/meter of said yarn is less than 15480/ W wherein D is the denier of said yarn and f is the number of filaments in said yarn.

6. A method as claimed in claim 5, wherein said falsetwist number is in a range from 15480/ l. f X 0.40 to 15480/ VWX 0.95 in turn/meter.

7. A method as claimed in claim 1, wherein the falsetwist number is controlled by adjusting the cross angle between a portion of said yarn just entered into the closed path and a portion of said yarn just emerged from the closed path.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5094068 *Mar 26, 1991Mar 10, 1992Murata Kikai Kabushiki KaishaFalse twister for yarn
US5136835 *Sep 17, 1991Aug 11, 1992Murata Kikai Kabushiki KaishaFalse twisting method for yarns and false twisting apparatus therefor
Classifications
U.S. Classification57/285
International ClassificationD02G1/02
Cooperative ClassificationD02G1/0266
European ClassificationD02G1/02B9