WO1992001093A1 - Process and device for making synthetic threads or fibres from polymers, especially polyamide, polyester or polypropylene - Google Patents

Abstract

The invention relates to a process for making synthetic threads or fully oriented filament yarn from polymers via the molten spinning of microfilaments which are cooled at least to solidification temperature behind a spinning nozzle and then heated for drawing purposes to a temperature above the melting point and at the same time blown with air to produce the necessary tension. Microfilaments having a single titer of less than 1.0 dtex are fed unbunched through the heating region and air is blown on them in counter-flow. It is thus possible fully to orient the microfilaments and obtain the synthetic threads thus formed at a relatively high drawing rate and with a short heating region. The synthetic threads have a relatively small expansion and may be used immediately, meaning that, owing to the fineness of the threads, it is possible, without further processing, to make particularly fine, smooth and silky textiles.

Description

 Method and device for producing plastic threads or fibers from polymers, in particular polyamide. Polyester or polypropylene

Bescnreinunq

The invention relates to a process for the production of plastic threads or fibers from polymers, in particular polyamide, polyester or polypropylene, by melt spinning microfilaments, according to which the microfilaments drawn off at a predetermined take-off speed behind the spinneret in at least one cooling zone Cooling solidification temperature and then heated to a temperature above the solidification point for the purpose of stretching in a heating zone and at the same time blown with a gaseous medium to increase the frictional resistance or generate the required stretching stress.

Such a method is known in which the plastic threads passing through the heating zone are blown with air in a crossflow. The plastic thread consists of 50 filaments - also called single capillaries - and has a capillary titer or single titer of at most 1.0 dtex, regularly of 3.0 dtex. The heating zone is formed by a relatively long heating tube, the length of which is 3 m. The filaments discharged from the spinneret are bundled after cooling, but before entering the heating tube to form the plastic filament to be heated for the purpose of stretching. Such bundling results in ^mutual contact of the filaments and consequently uneven heat treatment. This is disadvantageous for various reasons. First of all, the drawing process is disturbed because it is hardly possible to uniformly heat the filaments and consequently the plastic filament over its cross section to a temperature above the solidification point. The latter also applies to the intended increase in friction Resistance in order to generate the stretching tension required for the stretching. To make matters worse, the plastic threads are only blown in cross section anyway. Moreover, the take-off speed or winding speed cannot be increased arbitrarily in this known method and is only 3500 m / min. In this respect, not only is productivity unsatisfactory, but moreover the plastic threads produced by these known methods have a relatively high elongation, at least insofar as the individual titer is> 1.0 dtex. Plastic threads of this type require complex post-treatment for their textile processing. Finally, the plant for the production of such plastic threads builds relatively high, especially because of the long heating tube or heating shaft.

The invention has for its object to provide a method according to which fully stretched plastic threads or fibers (FOY = fill oriented yarn) can be produced with increased productivity, which are "suitable for immediate use - that is, without aftertreatment - in the textile industry" and can be processed into a particularly fine, supple or silk-like product. Furthermore, a suitable plant with a particularly low construction should be created.

The invention achieves this object in a generic method in that microfilaments with a single titer <1.0 dtex are passed through the heating zone in an unbundled orientation - namely in parallel operation - and blown in countercurrent by the gaseous medium - for example air . Microfilaments with a single titer of 0.4 to 0.8 dtex are preferably used. The teaching of the invention is first of all based on the knowledge that blowing the microfilaments in the counter-current process increases the frictional resistance and easily achieves the tensile stress required for complete drawing. Because countercurrent means higher air resistance, so that with increasing take-off speed, an increasing thread tension is generated, which results from the optimal drawing when the previously cooled microfilaments in the heating zone and consequently before the winding are heated up again to a temperature above their solidification point. Since, according to the teaching of the invention, the microfilaments pass through the heating zone without bundling, uniform heating of the microfilaments over their cross section is achieved. This uniform heating promotes the full orientation or stretching of the microfilaments and finally the resulting plastic filament. These plastic threads or the plastic fibers or staple fibers for staple fibers * yarns which can be produced therefrom are distinguished by a particularly low elongation and can be used without further aftertreatment due to their thread fineness, so that fine, an¬ pliant and silk-like goods can be made. - In the context of the method according to the invention, the stretching of the microfilaments therefore only takes place via the air resistance and the temperature in the heating zone. For this reason, a titer that is as small as possible, in particular capillary titer, is particularly favorable, because thread tension and thread temperature can then be influenced and adjusted more quickly and easily. In addition, it is possible to work with higher take-off speeds and consequently higher productivity despite a shortened heating zone. - 4th

Further features essential to the invention are listed below. Thus, the invention provides that the microfilaments are heated at 150 ° C to 250 ° C, preferably 220 ° C, in countercurrent and at a take-off speed> 3500 m / min to 8000 m / min, preferably 4500 m / min to 5500 m / min, are drawn through the heating zone. The heated microfilaments are expediently bundled only behind the heating zone, but before winding, so that they undergo particularly uniform treatment and drawing in the heating zone.

The invention also relates to a system which is particularly suitable for carrying out the claimed method because of its simple and compact construction. This system with at least one spinneret, a blowing shaft, a heating shaft, a preparation device, godets and a winding device is characterized in that the heating shaft on the outlet side produces countercurrent blowing devices, for. B. has blowing nozzles and thread take-off device is arranged 0.8 m to 1.2 m below the spinneret and has a shaft length of 1 to 1.5 m, preferably 1.2 m. This reduces the overall height by practically 50% compared to the known system with regard to the heating zone. Furthermore, the degree of stretching of the microfilaments and consequently produced plastic threads can be varied by changing the heating temperature in the heating shaft and the air supply in counterflow.

The invention is explained in more detail below with reference to a drawing which represents only one exemplary embodiment. The single figure shows a system according to the invention for the production of fully oriented plastic threads 1 from microfilaments 2. The basic structure of this system has a spinneret 3 for producing the microfilaments 2, which are cooled in a subsequent blowing shaft 4. Below the blowing shaft 4 there is a heating shaft 5 through which the microfilaments 2 are guided in an unbundled manner and in a parallel arrangement, heated and blown in countercurrent. This is indicated by arrows. The heating shaft 5 is followed by a preparation device 6, namely an oiler or corresponding spray nozzles. The bundling of the microfilaments 2 into the individual plastic threads 1 takes place in the area of the preparation device 6. The plastic threads 1 are then fed via godets 7 to a winding device 8 or a winding head and wound up. The heating shaft 5 is located 0.8 m to 1.2 m below the spinneret 3 in the thread take-off direction and has a shaft length of 1 m to 1.5 m according to the exemplary embodiment of 1.2 m. Furthermore, the heating shaft 5 has counterflow-generating blowing devices 9, for. B. blowing nozzles.

The plastic threads produced by the process according to the invention have an elongation <40%, preferably from 20 to 30%, and a strength> 3.6, preferably> 4 cN / dtex. Such values can be achieved if the take-off speed is 4500 m / min and the individual titer of the microfilaments is <1.0 dtex or the total titer of the relevant plastic threads is 30/48 dtex, i.e. the plastic threads consist of 48 microfilaments or single capillaries are formed. This is immediately clear from the table below.

Claims

Claims 1. Process for the production of plastic threads or fibers from polymers, in particular polyamide, polyester or polypropylene, by melt spinning microfilaments, after which the microfilaments drawn off at a predetermined take-off speed are cooled to at least solidification temperature in a cooling zone behind the spinneret and then heated for the purpose of stretching in a heating zone to a temperature above the solidification point and at the same time to increase the frictional resistance or to generate the required stretching tension with a gaseous medium, e.g. B. air, are blown, so that the microfilaments with a single titer • ■ 1.0 dtex are passed through the heating zone in an unbundled orientation and are blown in countercurrent by the gaseous medium. 2. The method according to claim 1, characterized in that the microfilaments are treated with a single titer of 0.4 dtex to 0.8 dtex. 3. The method according to claim 1 or 2, characterized in that the microfilaments in the heating zone at 150 ° C to 250 ° C, preferably 220 ° C, are heated in countercurrent. 4. The method according to any one of claims 1 to 3, characterized ge indicates that the microfilaments with a Abzuggeschwin¬ speed greater than 3500 m / min to 8000 m / min, preferably 4500 m / min to 5500 m / min are pulled through the heating zone 5. The method according to any one of claims 1 to 4, characterized gekenn¬ characterized in that the treated microfilaments are bundled behind the heating zone before winding. 6. Plant for carrying out the method according to one of claims 1 to 5, with at least one spinneret, a Blas¬ shaft, a heating shaft, a preparation device, godets and a winding device, characterized in that. that the heating shaft (5) on the outlet side counterflow-generating blowing devices (9), for. B. has blowing nozzles. 7. Plant according to claim 6, characterized in that the heating shaft (5) is arranged in the thread take-off direction 0.8 m to 1.2 m below the spinneret (3) and a shaft length of 1 m to 1.5 m, preferably , 1.2 m.