EP0063735B1 - Method for the production of textured polyester yarns from filaments with a non-circular cross-section, and yarns so obtained - Google Patents

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. H. 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 now mainly produced by simultaneous 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 case of the classic false-wire texturing method, in which already stretched yarns are presented to the texturing machine, it is known, for example from DE-B-2 101 315, 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 high-speed spun yarns, such as those used for. B. be described in DE-A-2 221 843.

The process described in GB-A-2 000 966 for the production of textured polyester threads with a multilobal cross-section is an exception. In this method, the thread cross sections are to be deformed less than usual during the stretch texturing process. To do this, however, it is necessary to use feed yarns that already have a very high degree of pre-orientation, such as are available, for example, from winding speeds of 5500 m / min and more. Such high spinning and winding speeds, however, lead to frequent filament breaks and fluff formation. In addition, the usual texturing used in this pre-literature uses a texturing heater from e.g. B. 200 ° C to very crimped yarn, the crimp if necessary by using a second heater of z. B. 195 ° C can be reduced in an additional fixing process.

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 nor a lint formation occurs. The filaments should continue to have only 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%, possibly even less than 10%.

Surprisingly, it has now been found that it is possible to process filament yarns with a high degree of pre-orientation to these desired yarns if they are subjected to a simultaneous drawing false twist texturing and are drawn and textured at a temperature which is less than about 30 ° C. above the freezing temperature (for definition see Ludewig, "Polyesterfaser", Akademieverlag Berlin (1975), pages 13 and 14) of the threads.

In the present invention, threads or yarns with a high degree of pre-orientation are understood to be those which have a birefringence of more than 65 × 10-a but less than 90 × 10-a, corresponding to spinning take-off speeds of approximately 4000 to 5000 m / min. The false twist applied to the yarns should be of the order of magnitude given by the Heberlein formula (see, for example, GB-PS-707859, 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 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 but under 90 x 10- ³ . In conventional spinning systems, such pre-oriented yarns are produced at spinning take-off speeds of over 4,000 to approx. 5,000 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 distinguished 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 extremely low deformation of the profile of the individual filaments leads to the use of yarns whose individual filaments, 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 amount of thermal shrinkage, to a lesser extent also the crimping, which can be represented numerically by the crimping. The glitter effect, ie the maintenance of the profile, remains in the temperature range according to the invention below about 100 ° C for polyethylene terephthalate largely independent of temperature, as can also be seen from Example 7 or Figure 4.

A special glitter effect, i. H. A particularly slight deformation of the sharp-edged profiles is observed when using spun threads or yarns, which were obtained with winding speeds of about 4,200 to 4,800 meters per minute on conventional spinning systems.

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 1,000 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 twist texturing method described in GB-A-852579 could also not be used as a model for the present invention since, like US-A-4173 860, it is limited only to the processing of slightly pre-oriented thread material. The process described in GB-A-852 579 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 which are more than 30 ° C. above the freezing temperature of the drawn polymer during simultaneous drawing and false-wire texturing. 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 a further negative effect that poorly oriented polyester threads, the z. B. were wound up with 1,000 or 2,000 meters per minute, do not allow to stretch evenly at temperatures below the freezing temperature. As can be shown in more detail in the examples below, it is necessary that the insert yarns for the drawn-filament texturing of profiled yarns have a birefringence of approximately 65 × 10-a to 90 × 10-a in order to maintain the profile well and to be low Get thermal shrink.

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 without the formation of lint. 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-A-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 process according to the invention provides yarns by means of a simultaneous draw texturing process, the preservation of the profile of which is even better than that of yarns which are produced by separate draw and texturing processes, as can be seen from the examples.

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.

• Die Glitzerkurven wurden mit Hilfe eines Zeiss-Gonio-meters GP₂ bestimmt, die genaue Meßmethode ist von Knopp in den « Lenzinger Berichten •, Folge 36, Februar 1974, Seiten 160-167 beschrieben. Zur eigentlichen Untersuchung werden parallel aufgewickelte Profilfäden unter einem Beleuchtungswinkel von 45° untersucht und die Intensität des reflektierten Lichts in Abhängigkeit vom Winkel gegenüber der Probenebene aufgenommen.

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 and the thermal shrinkage at 200 ° C are given as parameters 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 gonometer GP ₂ , the exact measuring method is 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 readily reproducible values which summarize the change or the deformations of the profile. In contrast, e.g. B. only small areas of individual filaments can be 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.

The false-wire-textured yarn according to the invention is characterized in that its profile maintenance, represented as the maximum value of the reflection curve, is at least 65% of the value of the smooth feed yarn and its thermal shrinkage at 200 ° C. is below 20%, preferably below 10%.

Example 1 - Comparative Example

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

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 a highly elastic texturing yarn (HE yarn) was produced from it using only one heater and a set yarn 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 twist sheave (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 (F _i ) 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 reflection 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 reflection values of the set yarn obtained (curve 2) as a function of the angle relative to the Sample level are reproduced.

Examples 2-6 Preorientation 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 ceramic discs of the "Kyocera" type. The other 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 which 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 from 4000 to 4900 meters per minute take-off speed in accordance with 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 over 75 x 10-3.
(See table on page 6 f.)

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 reflection values of the pre-oriented insert yarns, curves 2-5 those of the textured yarns made from them: 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 in normal stretch texturing drops to about half the value for smooth, non-textured yarn. 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 e.g. B. 160 ° C leads to the usual, highly voluminous yarns with the usual deformation of the filament cross-sections to hexagons.
(See table on page 8 f.)

Claims (3)

1. A process for making texturized multifilament yarns with profiled filaments, having a non-circular cross-section, the filament-forming substance of which consists of high-molecular weight polyester, by means of draw false twist texturizing of high speed spun feed yarns, characterized in that the feed yarns having a pre-orientation which corresponds to a birifringence of more than 65 x 10^-3 but less than 90 x 10^-3 are simultaneously draw false twist texturized at twist numbers, which correspond to at least usual figures according to Heberlein's formula

while heating the yarns to no more than 30 °C above the glass transition temperature of the polymer.

2. A process as claimed in claim 1, characterized in that simultaneous draw texturizing is carried out at room temperature without the use of a heating device.

3. A false twist texturized yarn composed of polyester filaments having a triangular profile characterized in that the yarn exhibits a profile retention, represented as maximum value of the reflectance curve, of at least 65 % of the value of the smooth feed yarn and a heat shrinkage at 200 °C of below 20 % preferably below 10 %.

Images