DE2117659A1 - Process for making threads and fibers - Google Patents

Description

FARBWEHKE HOECHST AG. formerly Master Lucius & Brüning File number: - HOE 71 / F o9o

Date: _{s # April 1Q71} - Dr.vF / Gn

"Process for the production of threads and fibers"

The invention relates to a method for producing threads and fibers by melt-spinning capillaries made of synthetic, linear polymers by means of a heating element between the spinneret and take-off godets with take-off speeds of over 2ooom / min.

For the production of synthetic threads and fibers from linear polymers, such as polyalkylene terephthalate, processes are known, in which in a first work process the threads are spun from the melt and, after cooling, wound on bobbins and in a second work process on special devices, usually under the action of heat, to a multiple of their original Length can be stretched, creating the desired textile properties.

There are also methods and corresponding devices have become known that the spinning and drawing continuously in one Carry out the process. These machines require a relatively high technical effort, which is particularly economical for questions fine titer. For example, heated rollers are common for the stretching process, and those that are also used for the high speeds must have sufficient temperature constancy.

Attempts have therefore been made to produce oriented threads without special stretching devices to manufacture. According to US patent 2 Go4 667 this succeeds when spinning at speeds above 47oo m / min. Since these speeds bring great technical winding difficulties, methods of this type are currently only for Suitable for special purposes such as the manufacture of fleece.

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On the other hand, there is a method in Swiss patent specification 357 144 described after the emerging from the spinneret Threads are spun directly into a heating shaft at winding speeds from 13oo - 26oo m / min. The elongation c'e-r thus obtained Threads is however compared to conventional threads so high that their textile utility value is very low.

The object of the invention is therefore at present technical winding speeds to be controlled spun from the melt Threads made of linear polymers with the chemical structure of polyesters, copolyesters e.g. cationically dyeable polyethylene terephthalate, of polyamides, e.g. nylon 6 or nylon 66 and polyolefins with good textile quality. Particularly for fine individual and total titers this process is both extremely advantageous for both qualitative and economic reasons. However, the process is not only applicable to fine individual titers limited, as shown by the examples «

This aim was achieved according to the invention in that the capillaries in front of the heating element are cooled to the solidification temperature or below and then, with the simultaneous action of the thread tensile force built up by the friction in the surrounding gaseous medium, which must be equal to the drawing tension required under the given conditions, to temperatures above the solidification point are heated.

In a preferred embodiment, a shaft is used as the heating element used with jacket heating, the capillaries being heated essentially by convection.

According to another preferred embodiment of the invention Process are used as a heating element radiators. The use of an iron as a heating element is also advantageous. The heat transfer takes place essentially through intensive contact.

All synthetic, linear polymers derived from the Let the melt spin into capillaries, or threads or fibers,

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such as polyesters, polyamides, copolyesters and copolyamides or polyolefins, especially for example polyethylene terephthalate and its copolyester, poly- ε, -eaproamide, polyhexamethylene adipamide, Polyethylene, polypropylene and the like. These polymers are made into the finest single threads in the usual devices, the so-called capillaries, spun and according to the invention Process further processed. The capillaries then become threads or fiber cables, depending on their intended use summarized and processed as usual. Between the spinneret and the godets there is a heating element. The godets run at speeds of at least 2,000 m / min.

It is extremely important that the heating element is not directly is located under the spinneret, but that the capillaries initially when passing through an unheated zone or by blowing with kaiter Lui ς chilled zone have the opportunity to get under to cool their solidification temperature. A capillary then has reaches its solidification point under the spinneret when its diameter or its running speed no longer changes changes (see also Hamana, Matsui and Kato, Melliand Textile Reports 4, 1969, pp. 382-38S and 5, 1969, pp. 499-5o3). This paralysis is with the various polymers from the point of view of the high cooling rate occurring under the nozzle of the capillaries.

Polyäthylter ^ phthalat, for example, has a low rate of crystallization. The rapid cooling directly under the nozzle leads to practically amorphous filaments. The solidification temperature corresponds to the glass transition temperature. Of course Vi measurements result in larger structures, e.g. in polyethylene terephthalate chips, higher freezing points; in the limit of infinitely slow cooling, the freezing point then falls by the crystallization that took place with the crystalline melting point together.

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For polymers that have high crystallization rates, such as polyethylene, crystallization occurs very quickly under the spinneret. The solidification of the capillaries occurs during cooling already at the crystallite melting temperature on. This can be seen in the course of the thickness of the capillaries (no more reduction in thickness) and at a stop point in the cooling curve of the capillaries, which is caused by the free / grounding heat of crystallization.

For polymers with medium crystallization rates, such as e.g. Polyamides or polybutylene terephthalate, can under the spinning conditions assign the solidification point neither to the glass transition temperature nor to the crystallite melting purite; it lies between the two values.

If the capillaries have not cooled down to below the solidification temperature before reaching the heating element, then a molten unoriented filament reach the heating element. The conditions would then correspond to direct spinning the point at which the heating element begins. The spinneret can be thought of as being placed at this point. In such a procedure threads with a lower orientation result (Swiss patent 357 144).

After the capillaries have been cooled to their solidification temperature or to temperatures below, they are below simultaneous action of the thread tensile force built up by the friction in the gaseous medium, which is at least equal must be the required yield stress, heated to temperatures above the solidification point.

The cooling to below the solidification temperature is preferred, by blowing purified air at room temperature, however, can can also be made lively differently.

This heating of the capillaries to temperatures above their solidification temperature takes place with the aid of a heating element, preferably with the help of a heated shaft, which the capillaries

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run through, but it is also advantageous to use Radiant heaters or even guiding the capillaries over a heated iron. The required minimum distance of the spinneret to the upper edge of the heating element depends on the material of the threads, on the spinning temperature, on the individual titer of the Capillaries, the total titre of all capillaries spun through a nozzle plate into the heating tube, the withdrawal speed and the cooling conditions between the spinneret and the upper edge of the heating element. In practice, for example, one determines the required Minimum distance for polyethylene terephthalate in such a way that for the take-off speed, which is usually chosen for technical reasons, which leads to the desired titer, determines the temperature along the thread, for example with the thermal cross from Hastings, as described below, this surface temperature of the thread against the distance from the spinneret and that belonging to the solidification point in this curve Defines the minimum distance. In Figure 2, these curves are for threads made of polyethylene terephthalate with the specific viscosity of 95o, measured on a 1 percent by weight solution in a mixture of phenol / tetrachloroethane with 3: 2 parts by weight 25 ° C, the titer dtex 15of5o and dtex 75f5o ohre transverse blowing and shown without heating shaft. The spinning kettle temperature was 300 ° C. The measurement of the surface temperature of the spinning thread takes place with the thermal cross from Hastings (Hastings-Raydist, Inc., Hampton, Virginia USA, "Match Temperature" Pyrometer). This The device works according to the compensation principle, whereby the crosshair, which is placed on the thread to be measured, can be heated. For Fig. 2a (dtex 15oföo) and Fig. 2c (dtex 75f5o) was the winding speed 35oo m / min, for Fig. 2b (dtex 15of5o) and Fig. 2d (dtex 75f5o) comparatively 2,000 m / min. The representation is clear it can be seen that for the same distance from the spinneret, the lower the thread temperature, the lower the same Ti tor is the take-off speed; for the same withdrawal speeds is understandably the temperature for finer titers less than for larger thread sizes.

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This required minimum distance from the upper edge of the heating element, for example the heating pipe, can be exceeded as desired; However, efforts will be made to keep the distance between the nozzle plate and the upper edge of the heating element as small as possible, otherwise the systems will be damaged be extended undesirably.

In any case, the heating element must be sufficient for the capillaries heat so that they reach a temperature between their solidification temperature and the melting temperature. When the threads without the heating element or without a temperature on the heating element achieve in this area ^ u, otherwise under the inventive Conditions are treated, they no longer have the good textile technology obtained according to the invention Properties on.

Simultaneously with the rewarming of the previously to temperatures Capillaries cooled below the solidification temperature are removed from the capillaries below the heating element with the aid of Pull-off godets drawn off at a predetermined take-off speed. This builds up due to friction on the surrounding gaseous Medium has a thread tension that must be at least equal to the required stretching tension. It finds the stretching of the Capillaries instead. If the tension applied to the capillaries is less than the required draw tension, it will Material not stretched out, i.e. there is still a minimum in the K-D diagram.

The use of a heating element changes the characteristics of the filament temperature curves for two reasons:

Once the filament is reheated on the heater to temperatures which are in any case above the solidification temperature must lie. Second, flrdct under the influence of Crystallization and orientation take place in the presence of tension and tension,

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a process which in principle is compared to a stretching process can be; i.e. a difference in speed and thickness can be observed on the threads before and after the heating device. Addicted on the design of this heating device, its temperature and the parameters specified by the threads speed ratios of up to 1: 2 can occur. Which actually directs cooling of the threads The decisive speed below the spinneret is therefore lower than the winding speed specified by the pair of godets. The threads will thus already reach the solidification temperature at a smaller distance from the nozzle. To the However, this is counteracted by the larger thread thickness, which is calculated according to the speed ratios can.

The required length of the heating element depends on its design; in any case it must be chosen so that the the desired thread temperature for orientation and crystallization is reached. Temperature and speed in a certain context, as FIG. 3 shows using the example of the 100 ° C. vapor shrinkage for dtex 15of5o 100 ° C steam shrinkage, a 5o cm long piece of thread is placed in a steam cabinet for 7 minutes and then the difference in length measured. A heated shaft was used as the heating element; the temperatures were 30 ° C (curve a), 15o ° C (curve b) and 22o ° C (curve c).

Those coming from the spinneret to below the solidification temperature cooled and in the heating element again to above the solidification temperature with simultaneous build-up of the Stretching tension warmed capillaries are after a certain cooling zone after the heating element via a preparation ~ facility pulled. The withdrawal speed with the help

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of the take-off godets is at least 2ooo m / min,

If no contact surfaces are used for this rewarming, so the thread tension is essentially dependent on the take-off speed, the length of the free path between Blow-in shaft ends and take-off rollers, the kinematic viscosity of the gaseous medium in the heating element and thus of its temperature as well as its length and the ratio of thread thickness to the sum of the capillary surface.

The speed and the free thread path between the nozzle and the lower edge of the heating device should always be increased lead to an increase in the tensile strength of the thread and thus also in the orientation «Taking into account the temperature of the heating element however, a linear course is not to be expected, since the physical processes are complex and closely related between thread speed, thread temperature, thread tension and crystal structure prevails. The influence of the number of the capillaries is obvious, since e.g. in the case of the same total titer the ratio of the surface area of the square root " corresponds to the ratio of the number of capillaries.

The exact, value-based detection of the forces is difficult to the extent that the measuring element causes a Change in physical equilibrium takes place. The additionally introduced frictional force can affect the speed distribution and

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change the sum of the air friction forces as a result. . ,

The elongation of these threads produced by the process shown can be varied within wide limits without having to use the receives undrawn points in the thread that occur on the usual draw-twisting machines with lower draw ratios.

It has been shown that threads with the high elongation values, as can be obtained by the method according to the invention, can be advantageous for various areas of application. If threads made of polyethylene terephthalate with an elongation of approx. 4o % are placed in a false-twist texturing machine, crimp values 10-3o% higher are achieved at the same spindle speed compared to the usual threads with approx. 25 % elongation. Conversely, there is the possibility of increasing the texturing speed by the corresponding amount with the same curl values and thus improving the profitability of the texturing process. However, the elongation can only be increased up to a limit of about 50%, since otherwise the resistance of the crimp to high loads leaves something to be desired. This excludes, for example, the use of threads that have been manufactured according to the method of Swiss patent specification 357 144 ..

Also noteworthy is the high ink absorption speed, which is presumably not only due to the low average orientation, but also to a core-shell effect a reduced orientation of the capillary height. Comparative Dyeing tests with threads of a corresponding average orientation, which are caused by a lower draw ratio on conventional draw twisting machines were produced (but with undrawn areas) indicate this.

Although not generally required, a subsequent additional stretching process can be added for special cases when special textile-technological properties are desired. This process can be carried out directly with the inventive Process can be coupled, but can also be in one

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- be carried out in a separate operation. ,

The manufacture of nonwovens is an extremely advantageous field of application . So it is possible to use spunbonded fabrics from capillaries fine single titer, whereby the textile data such as strength and elongation are adapted to the special requirements can be.

The method according to the invention is illustrated by the following figures as well as the examples are explained in more detail:

Fig. 1 shows the schematic diagram of an apparatus for carrying out the method.

FIG. 2 shows the dependence of the temperature of a spun thread on its distance from the spinneret for two take-off speeds and two different titers without blowing and without too ·? additional heating element according to the state of the art. Fig. 3 shows the curves for the loö ° 0 ~ steam shrinkage of threads of the titer 15of5o depending on the withdrawal speed and the temperatures of a heating element of 30 ° C (curve a), 150 ° C (curve b) and 22o ° C (curve c).

4 shows the force-elongation diagrams of the threads produced according to Example 2 and Example 3 (according to the prior art).

Fig. 1 shows a spinning plant for carrying out the method in a simplified form. The melt, for example polyethylene terephthalate, is pressed through the spinneret 1, which has the desired number of capillary bores. In a blowing chamber 2, the threads 3 are blown with a cooling gas flow, usually conditioned air, in a cross flow and cooled to the solidification temperature or below. The subsequent heating device 4 heats the threads on contact surfaces and / or by convection and / or radiation to temperatures above the solidification point and below the melting temperature. After a certain cooling zone, the threads are pulled over a preparation device 5. The haul-off speed is determined by the speed of the pair of godets 6 "Aufgewiek ^ l ^^ i ^ JWy · ^ # ^{äcäeB ailf} a suitable one

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Flushing device 7. In the case of applying the method to the In the manufacture of fibers, the capillary bundles can be combined in several places after the godets and in corresponding Devices such as jugs can be deposited.

The method is intended to be further illustrated by the following examples however, it is by no means limited to these uses limited.

Example 1 ;

A spun thread made of polyethylene terephthalate with a specific viscosity of 95 °, measured on a 1% by weight solution in a mixture of phenol / tetrachloroethane with 3: 2 parts by weight at 25 ° C., is conveyed from a spinneret at 17.5 g / min spun at a temperature of 300 ° C. In a known blowing damage of 50 cm length, the thread is blown in cross-flow with air at room temperature and thereby cooled to a temperature of approx. 40 ° C., which is below the solidification point. The check is carried out by the Hastings temperature measuring device and comparatively also by optical observation of the thread thickness. The thread is then pulled through a heating tube 2oo mm in diameter and 3 m in length. The temperature on the shaft wall is kept constant at 2oo ° C. The heating element begins at a distance of 70 cm from the spinneret. The thread leaves the heated shaft at a measured temperature of about 160 ° C. and is provided with preparation 30 cm after the shaft by running over a rotating preparation disk. The winding speed is 35oo ra / min, the titer dtex 5050. The textile data of the threads are listed in Table 1. Strength and elongation were determined on a Zwick Z 1.3a device with a clamping length of 500 mm and a tear time of 20 seconds. For the measurement of the boiling or hot air shrinkage, Io m thread is wound in a strand and Io min is treated without tension in boiling water or in a hot air cabinet. The length measurement takes place under a preload of 0.05 p / dtex and thread. The thread tension, measured between the heating shaft and the preparation disk, is approx. 6o p. A voltage of 1.2 p / dtex is calculated based on the final titer.

Test-dyed ribbons of this material are characterized by a excellent coloring quality. In addition, with the same dyeing

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• conditions the strong depth of color compared to normally drawn threads is essentially due to a high speed of ink absorption.

Table 1

dtex Example 1 • Ex . 2 Ex. 3 Ex . 4th Titer p / dtex 5o f 5o 15o f 5o 15o f 5o 15o f 5o strength % 41 36 28 24 strain % 28 39 62 68 Cooking shrinkage 6th 5 8th 58 2oo ° C hot % air shrink Io 9 12th 69 Example 2:

A spun thread made of polyethylene terephthalate consisting of 50 individual capillaries the specific viscosity of 95o, measured as indicated in Example 1, is delivered at 52.4 g / min spun from a spinneret at a temperature of 295 ° C. The further treatment of the thread corresponds to that of the example 1, in this case a thread temperature after the blowing of approx. 55 ° C and, after the heater, of 15o ° C. The thread tension here is 0.85 p / dtex, wound on the titer becomes dtex 15of5o. The measured textile data are contained in Table 1.

If the material is presented to a texturing machine, surprisingly high curl values are found with a slight reduction in the lead to compensate for the texturing tension that is lower than that of conventional production goods with otherwise the same machine setting. For highly elastic material the crimp values are approx. 15-2o%, for the shrunk set type approx. 3o % above the normal values. If the aim is to achieve the same power values, there is the possibility of increasing this by 15-3o% with the same texturing spindle speed, which for technical reasons specifies the maximum working speed, and thus making the working process much more economical.

If, on the other hand, threads with more than 5o% elongation, as is the case with a

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drive accruing according to the Swiss patent 357 144, textured according to the usual false-wire process, then the received Crimping not resistant to higher loads. If the load corresponds to that of wearing clothes, the curling sheets are pulled out.

Example 3 :

A spun thread made of polyethylene terephthalate consisting of 50 individual capillaries the specific viscosity of 95o, measured as indicated in Example 1, is at 52.4 g / min Fördeimng from a Spinneret at 295 ° C directly into a heating shaft 2 m long and 220 ° C, corresponding to Example 3 of the Swiss patent 357 144 spun, so that the threads are cooled to the solidification point for the first time after the heating shaft. After this Passing another 2 m long, but unheated shaft, the threads are provided with preparation and as in in our example 2 wound up at 35oo m / min to dtex 15of5o. The thread tension in relation to the final denier is 0.4 p / tex. the Textile values according to Example 2 could not be achieved, as can be seen from Table 1. The difference is also noticeable in the KD diagram (Fig. 4). Despite the higher winding speed compared to the claims of Swiss Patent 357 144, a saddle (curve b) can still be seen in the KD line, which indicates a poorer orientation. Through a process according to the present invention may be otherwise the same Conditions of this deficiency are eliminated (curve a).

Example 4 ;

As in Example 2, dtex 15of5o was produced on the same system with a shaft temperature of 70 ° C. By the thread a temperature of 6o C was measured after leaving the shaft; the freezing point was thus no longer reached. As expected, there is a lower strength, higher elongation and high shrinkage values as listed in Table 1. These threads are useless in terms of textile technology without subsequent stretching.

In this speed and temperature range it is also possible to obtain threads which have a higher boiling shrinkage than Have 200 ° C hot air shrinkage; i.e. when treating with

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higher temperature occurs due to the special physical Structure of the threads first a shortening and then a> lengthening.

Example 5:

A spun thread made of polycaprolactam consisting of single capillaries the relative solution viscosity of 2.9, measured on a 1 percent by weight solution in 96% sulfuric acid at 20 ° C, the spinning is carried out at 9.2 g / min from a spinneret at a temperature of 300 ° C. In a per se known Blowing shaft 18o cm long is the thread in the cross flow Air blown at room temperature. Then he passes the 9 m long spinning shaft, in which the air flow speed without a running thread is zero. At the end of the spinning shaft, the thread runs over a 1 m long iron, which is set to 160 ° C is heated. Then it touches a rotating roller that is wetted with a preparation agent. The winding speed is 27oo m / min, the titer 33flo.

The following textile data were determined on the threads:

Titer 33 dtex

Strength 5, ο p / tex

Elongation 4o %

Cooking shrinkage lo, 5%.

In FIG. 2, the temperature in ⁰ C is plotted on the ordinate and the distance from the spinneret in cm is plotted on the abscissa.

In FIG. 3, the ordinate shows the 100 ° C. vapor shrinkage in%, and the abscissa shows the withdrawal speed from the heating element in m / min.

In FIG. 4, the strength of the threads in pond / dtex is plotted on the ordinate and the elongation in% on the abscissa.

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Claims (4)

PATENT CLAIMS: / l. _{: A} process for the production of threads and fibers by melt spinning of capillaries from synthetic, linear polymers by means of a heating element between the spinneret and the haul-off godets with haul-off speeds of over 2ooo m / min, characterized in that the capillaries are cooled to the solidification temperature or below before the heating element and then are heated to temperatures above the solidification point with the simultaneous action of the thread tensile force built up by the friction on the inexistent gaseous medium, which must be equal to the required tensile stress. 2. The method according to claim 1, characterized in that a shaft with jacket heating is used as the heating element, wherein the capillaries are heated essentially by convection. 3. The method according to claim 1, characterized in that the heating element Emitters are used. 4. The method according to claim 1, characterized in that an iron is used as the heating element, on which the Y / arine transition essentially takes place through intensive contact. L e r s e i t e