EP0063735A2 - Method for the production of textured polyester yarns from filaments with a non-circular cross-section, and yarns so obtained - Google Patents

Abstract

The invention relates to a method for producing textured multifilament yarns with profiled filaments made of polyester by stretching false-twist wire texturing, multifilament yarns with high pre-orientation corresponding to a birefringence of more than 65 × 10 <-> ³ being used as supplier yarns, which without reducing the number of twists, but at temperatures, which are not more than 30 ° C above the glass transition temperature (freezing temperature) of the polymer, are simultaneously drawn and textured with false wires, as well as the glitter yarns obtained, the cross-sectional profiles of which have been largely preserved through this special texturing process.

Description

The present invention relates to a method for producing textured profile yarns, in which the profile has largely been preserved, by simultaneous stretching and false-wire texturing of pre-oriented polyester yarns, and the glitter yarns obtained thereby.

Glitter yarns are required for special fashionable effects, i.e. textured yarns that consist of single filaments with a sharply defined profile and that have only a relatively low crimp. For reasons of cost, textured yarns are mainly produced today by simixltanes stretch texturing of fast spinning yarns. With simultaneous stretch texturing, however, the tendency of the filaments typical of false-wire texturing increases, regardless of their initial cross section, to assume a more or less hexagonal cross section, such as the z. B. by Bigler in "Melliand Textile Reports" 1969, page 85 ff.

In the classic false-wire texturing method, in which already stretched yarns are presented to the texturing machine, it is known, for example from DE-AS 21 01 315, that a lower twist and also a somewhat reduced texturing temperature lead to better maintenance of the profile. However, these measures do not lead to success in simultaneous stretch texturing, not even when using so-called fast. B. be described in DE-OS 22 11 843.

One possibility for producing yarns from sharply profiled individual filaments which have a weak crimp is described in EP-OS 11 915. In this process, quickly spun yarns made from profiled material are subjected to a gear crimping process. As is known, this crimping process leads to less deformation of the individual filaments. The deformations are mostly limited to the locations of the individual filaments where the filaments were forced to change direction. The gear crimping method has the disadvantage, however, that all filaments of a yarn are forced to have a uniform and in-phase crimp, so that undesirable pattern formations inevitably occur in the textile fabrics produced therefrom. In contrast, the false twist crimp achieves a three-dimensional, statistically uniform crimp. Pattern formation is not observed when processing such yarns.

The above-cited EP-OS 11 915 can also be seen that it was previously believed that it was not possible to produce threads with relatively weak crimp using a false wire method at all.

It was therefore still an object to provide a process for the production of textured profiled yarns in which rapidly spun polyester filament yarns can be simultaneously stretched and false wire textured while maintaining their profile characteristics, without the known and undesirable deformation of the filaments into hexagons occurring. The filaments should continue to have a low bulk, which corresponds approximately to the so-called set yarns. The shrinkage capacity of these yarns, expressed by thermal shrinkage at 200 ° C, should not exceed 20%, if possible even less than 10%.

Surprisingly, it has now been found that it is possible to process high pre-orientation filament yarns into these desired yarns when subjected to simultaneous draw false-twist texturing, drawing and texturing the yarns at a temperature less than about 30 ° C above that Freezing temperature (for definition see Ludewig, "polyester fibers", Akademieverlag Berlin (1975), pages 13 and 14) of the threads.

Threads or yarns with a high degree of pre-orientation are understood to mean those which have a birefringence of more than 65 × 10 ^-3 , corresponding to a spinning take-off speed of approximately 4000 meters per minute or more. The false twist applied to the yarns should be of the order of magnitude that is given by the Heberlein formula (see, for example, GB-PS 707 839, claim 1) or even higher.

The simultaneous stretching false wire texturing required according to the invention is preferably carried out at room temperature without the use of a heating device.

The birefringence of the insert yarns is usually below 120. 10 ^-3 , preferably even less than 90 .. 10 ^-3 , ie, in conventional spinning systems, spinning take-off speeds below 5,000 m / min are mostly used.

The method according to the invention requires the use of spinning yarns or threads that already have a high degree of pre-orientation, which, for. B. can be described by a birefringence of over 65 x 10 ^-3 . In conventional spinning systems, such pre-oriented yarns are produced at spinning take-off speeds of over 4000 meters per minute. It has now been found that such highly oriented, but not yet fully drawn, spun threads can be converted into a weakly crimped texturing yarn with the help of false-wire texturing machines if these threads are exposed to the full false twist and a simultaneous drawing at temperatures up to 30 ° C. above the freezing temperature. Under these selected conditions, textured yarns are obtained which are characterized by a slight crimp - for example that of set yarns - and in particular have no deformations in the profile of the individual filaments. The missing or extraordinarily slight deformation of the profile of the individual filaments leads to the use of yarns, the individual filaments of which, for. B. have a sharp-edged triangular profile, to glitter yarns that are particularly in demand for fashionable effects. The threads textured in this way also have low thermal shrinkage at 200 ° C.

With a given pre-orientation of the insert yarns within the range according to the invention, the drawing and texturing temperature then also determines the level of the thermal shrinkage, to a lesser extent also the crimping, which can be represented by the crimping. The glitter effect, ie the maintenance of the profile remains largely independent of temperature in the temperature range according to the invention below about 100 ° C. for polyethylene terephthalate, as can also be seen from example 7 or FIG. 4.

A special glitter effect, ie a particularly low deformation of the sharp-edged profiles is observed when using spun threads or yarns, which with winding speeds of about 4200 to. 4800 meters per minute were obtained on conventional spinning systems. With a further increase in the take-off speed and a further increase in the pre-orientation to values of the birefringence of more than 120 x 10 ^-3 , an increase in the fluff is observed, which, at least when the currently used spinning systems and texturing machines are used, prohibits the use of these yarns.

The method according to the invention differs fundamentally from the method described in US Pat. No. 4,173,860. In this procedure of the previous literature, only slightly oriented yarns, e.g. B. were obtained with a winding speed of 1000 meters per minute, stretch textured. When such yarns are drawn, a clearly visible drawing point is formed, at which the diameter of the individual filaments is abruptly reduced and tangible drawing heat is released. It should be particularly pointed out that, according to this preliminary literature, stretching of polyester multifilaments is only possible if a small heater is additionally used, which in turn ensures that the freezing temperature is at least exceeded, which is significantly higher for polyesters than for polyamides. Such a heater is required in any case when using low-oriented yarns, since otherwise an unevenly drawn yarn, in which drawn and undrawn points alternate, is obtained.

The simultaneous false-wire texturing method described in GB-PS 85 25 79 could not be used as a model for the present invention, since, like US Pat. No. 4,173,860, it only has a slight processing effect pre-oriented thread material is limited. The process described in GB-PS 85 25 79 requires drawing at least in a ratio of 1: 2. In addition, the examples are only directed to the processing of polyamide yarns in which cold drawing is possible. When this method is used, a strongly crimped yarn is obtained after the crimp has been triggered; the individual filaments have the typical deformation into hexagons. Such yarns show no or only an extremely slight glitter effect.

It is crucial for the method according to the invention that the threads or yarns do not assume temperatures during simultaneous drawing and false-wire texturing which are more than 30 ° C. above the freezing temperature of the drawn polymer. These temperatures are surely exceeded when the customary polyamide threads are drawn, forming a drawing point. As a result, deformation of the profile of the individual filaments is unavoidable in stretch texturing. The same applies accordingly to poorly oriented polyester filaments. Here, however, there is another negative effect that poorly oriented polyester threads, the z. B. were wound up with 1000 or 2000 meters per minute, do not allow to stretch evenly at temperatures below the freezing temperature. As can be shown in detail in the examples below, it is necessary that the insert yarns for the drawn false-twist texturing of profiled yarns have a birefringence of about 65 x 10 ^-3 to 120 x 10 ^{-3 in} order to achieve a good one

Preservation of profile and low thermal shrinkage.

A major advantage of the method according to the invention is that for the first time a stretch texturing method could be made available which largely avoids the usual deformation of the filaments into hexagons. The effect of this profile maintenance leads to a significant improvement in the glitter effect in threads with triangular profiles. The method according to the invention is also suitable for obtaining different types of cross sections such. B. multilobal cross-sections with anti-glitter effect, as described in US-PS 38 46 969 ..

The crimp values of the glitter yarns produced according to the invention are in the range of the so-called set yarns, that is to say yarns which have been produced on so-called double heater false-wire texturing machines or by a separate steaming process. In contrast to this, however, no heater or only a heater with significantly lower temperatures than usual is required in the method according to the invention.

The method according to the invention thus surprisingly delivers yarns with little crimping and low thermal shrinkage without the use of heat or only using relatively low temperatures, which according to the prior art can only be achieved by false-wire texturing processes with a texturing heater temperature of over 200 ° C. and a similar temperature of the second set heater can be obtained, or by a steaming process of the wound-up textured yarns following the texturing. In addition, the method according to the invention provides yarns with a simultaneous draw texturing process, the profile maintenance of which is even better than that of yarns Texturing processes are produced, as can be seen from the examples.

This maintenance of the profile in the stretch texturing method according to the invention is also surprising, since the strong deformation of the filaments to form hexagons has previously been regarded and accepted as an unpleasant characteristic of this method in simultaneous stretch texturing.

The following examples show the comparison of the textured profiled yarn according to the invention with classic HE and set yarns, as well as the delimitation of the claimed area of pre-orientation and the stretching and texturing temperature based on the parameters crimping, thermal shrinkage and glitter effect.

The crimping EK according to DIN 53 840 and the crimp shrinkage at 120 ° C as a relative change in the yarn lengths under a preload of 0.01 cN / tex before and after the heat treatment at 120 ° C, the thermal shrinkage at 200 ° are given as parameters C as a relative change in length under a preload of 0.02 cN / tex before and after heat treatment at 200 ° C, and the glitter curve according to Knopp as a measure for maintaining the profile, as described below:

The glitter curves were determined with the aid of a Zeiss GP ₂ goniometer, the exact measurement method being described by Knopp in the "Lenzinger reports", episode 36, February 1974, pages 160-167. For the actual examination, profile threads wound in parallel are examined at an illumination angle of 45 ° and the intensity of the reflected light is recorded as a function of the angle relative to the sample plane.

This method of measurement has the advantage that, in addition to its good practical relevance, it provides easily reproducible values which summarize the change or deformation of the profile. In contrast, e.g. B. only small areas of individual filaments are checked and evaluated in microscopic examinations. A summary evaluation, which also takes into account deformations that do not always occur, is practically only possible via light reflection measurements on a large number of individual filaments.

Corresponding reflection measurements were carried out both on the starting yarns and on the textured yarns produced therefrom. The measurement curves obtained are shown in FIGS. 2-4.

The values are given in arbitrary units, 100 divisions correspond to the reflection value of the polished black glass plate belonging to the measuring device at an angle of 45 °, the so-called black standard. Figure 1 shows the reflection values of this black standard as a function of the angle relative to the sample plane.

The maximum value of the reflection of the measured yarns at an angle of 45 ° was also included in the tables.

Example 1 - Comparative Example

A stretched multifilament yarn ("Kops-Ware") made of polyethylene terephthalate dtex 76f24 glz, the filaments of which had a well-defined triangular profile, served as the starting yarn.

The textile values of this yarn are listed in the table below. This starting yarn was presented to a false-wire texturing machine from Barmag AG of type FK 5 and from it a highly elastic texturing yarn (HE yarn) was only used one heater and another set yarn made using 2 heaters. The other working conditions are summarized in the table below. A Barmag friction swirl device, which consisted of 3 sets of 3 disks made of sintered ceramic, served as the swirl device.

From the values in this table it can be seen that in both cases the yarn was handed down slightly on the first heater and during texturing, so that the threads were never drawn. In the set process, a further transmission of the yarn was carried out in the usual way during the treatment in the second heater. To characterize the twist distribution, the D / Y ratio was given, ie the quotient of the circumferential speed of the twister disks (D from "disc") and the linear speed of the yarn (Y from "yarn"). Another specified process parameter is the tension of the threads before the swirl generator (F1) and after the swirl generator (F ₂ ). (CN) was chosen as the unit of measurement for these voltage measurements.

From the table and FIGS. 2 and 3 it can be seen that when texturing already stretched yarns, the reflection value at 45 ° decreases by more than 40% compared to the non-crimped material. Figure 2 shows the reflectance values of the starting material (curve 1) and the HE yarn obtained (curve 2), while in Figure 3 in addition to the starting material (curve 1), the reflectance values of the obtained set yarn (curve 2) as a function of the angle relative to the Sample level are reproduced.

Examples 2 - 6 pre-orientation series

The following examples show the influence of pre-orientation on the decisive parameters of profile / glitter and 200 ° C thermal shrinkage.

Polyethylene terephthalate multifilaments, which had been obtained at winding speeds of 3000 to 4900 meters per minute, served as insert yarns. The individual filaments each had a sharp-edged profile that corresponded to an equilateral triangle in cross section. The other properties of the threads and the texturing temperature are summarized in the table below.

The texturing was carried out on converted stretch twisting machines which were equipped with a contact heater of 125 cm in length and had friction swirlers from Fischer AG with 3 x 3 "Kyocera" type ceramic disks. The further process conditions, in particular the surface temperature of the texturing heater, are summarized in the table below, as are the test values of the textured threads obtained. The relative reflection value, which was determined as described in Example 1, was again used to characterize the deformation of the profiles that occurred during texturing.

From the table it can be seen that the maximum reflection values, ie at an angle of 45 °, increase with increasing birefringence of the insert yarns. Particularly good values were obtained between a take-off speed of 4000 and 4900 meters per minute, corresponding to a birefringence of 65 to 85 x 10 ^-3 .

In contrast, the thermal shrinkage decreases with increasing orientation of the insert yarns and drops in the pre-orientation range according to the invention to values below 10% with a birefringence of more than 75 _x 10 ^-3 .

Example 7 - Temperature series

Starting yarns according to Example 5 were simultaneously stretch-textured, the temperature of the texturing heater being changed between room temperature, ie without a heater, and 160 ° C. The results of the reflection value determinations are shown in FIG. 4. Curve 1 shows the reflectance values of the pre-oriented insert yarns, curves 2-5 those of the textured yarns made from it: curve 2 without heater - curve 3 at 80 ° C - curve 4 at 100 ° C and curve 5 at 160 ° C. From this it can be clearly seen that the reflection value at an angle of 45 ° as a measure for maintaining the profile with normal stretch texturing to about half the value for smooth, non-textured yarn. sinks. At texturing heater temperatures up to about 100 ° C, on the other hand, there are values of about 75% of this normal value. The choice of texturing temperatures can then be chosen within the limits of the invention according to the desired thermal shrink. A texturing temperature of, for example, 160 ° C leads to the usual, highly voluminous yarns with the usual deformation of the filament cross-sections into hexagons.

Claims (4)

1. A process for the production of textured multifilament yarns with profiled filaments, the thread-forming substance of which consists of high molecular weight polyesters, by stretching false-wire texturing, characterized in that multifilament yarns with high pre-orientation, which have a birefringence of more than 65 x 10 ^-3 , without reduction in the twist number as the supply yarns Simultaneously falsewire textured and drawn, the yarns not being heated more than 30 ° C above the glass transition temperature of the polymer. 2. The method according to claim 1, characterized in that the simultaneous stretch texturing takes place without the use of a heating device at room temperature. 3. The method according to claim 1 or 2, characterized in that the birefringence of the insert yarns is below 120 x 10 ^-3 , preferably in the range 70 to 90 x 10 ^-3 . 4. False-wire textured yarn made of polyester filaments with a triangular profile, characterized in that a profile maintenance, represented as the maximum value of the reflection curve, is at least 65% of the value of the smooth supply yarn and its thermal shrinkage at 200 ° C is less than 20%, preferably less than 10%.

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