WO1989009298A1

WO1989009298A1 - Process and device for producing spunbonded fabrics

Info

Publication number: WO1989009298A1
Application number: PCT/DE1989/000176
Authority: WO
Inventors: Franz Fourné
Original assignee: Automatik Apparate-Maschinenbau Gmbh
Priority date: 1988-03-21
Filing date: 1989-03-21
Publication date: 1989-10-05

Abstract

Process for producing spunbonded fabrics from synthetic polymers, in which, after spinning and cooling, the yarns which form the spunbonded fabric are placed widthwise, in the form of a warp, on a moving surface, for example a conveyor belt. Before the yarns are placed on the moving surface, they are waved and extended simultaneously by the action of combing, non-contacting toothed rollers which distribute the yarns uniformly in the axial direction of the rollers.

Description

description

Method and device for spunbond production

The invention relates to a method and an apparatus for producing spunbonded nonwoven from synthetic polymers, in which the threads forming the spunbonded nonwoven after spinning and cooling as a wide thread chain on a moving surface, e.g. in the manner of a conveyor belt.

Spunbonded non-woven, textile-like fabrics are to be understood here, which are formed from continuous filaments directly during the spinning process, be it from melt- or solution-spun polymers or combinations of different polymers that are deposited on the moving surface, which are essentially in the normal direction moved to the direction of the threads to be placed. This means that it is not a tile made of threads that are torn into fibers of finite length after leaving the spinneret before they hit the moving surface.

For the production of the spunbonded nonwovens defined here, there are already a number of processes which have in common that the melted or dissolved polymer is spun with very little many holes is extruded. This is followed by a cooling section in the case of molten polymers and a hatching or hot gas section in the case of dissolved polymers for the extraction of the solvents. So that the threads formed in this way obtain sufficient fineness, strength and elongation, they are drawn off from the spinneret through the cooling or extraction section by means of take-off devices which are located either in or under the cooling or extraction section.

One of these methods uses compressed air-operated suction nozzles as the extraction device. After cooling, the threads are inserted individually or in bundles into these nozzles, so that the compressed air flow in a Venturi-like nozzle ensures that the threads are pulled further down. In this case, a thread speed of approximately 20-100 m / sec is achieved at the outlet end of these nozzles, thus giving the threads a desired pre-stretching. The threads or bundles of threads are more or less spread apart from the lower outlet ends of these suction nozzles, tangled down on a conveyor belt and transported on as a fleece.

Another method draws the threads at a higher take-off speed than the spraying speed at the spinnerets by blowing cooling air at higher speeds onto the threads close to the spinnerets, which also pulls them down by air friction and thereby pre-stretching them.

Since these methods mentioned do not result in any forced withdrawal from the nozzle and no forced drawing of the threads, a further method has also been used: the threads extruded through the nozzle bores and cooled or extracted underneath are removed by snowing valleys pulled and stretched and only placed on the conveyor belt after these rolls. In order to increase the stretching of the threads compared to the pre-stretching effect already achieved by rapid draw-off from the spinnerets, a plurality of rollers connected in series can be arranged with increasing peripheral speed, with, for example, the roller pulling off directly from the nozzles having a peripheral speed of 10-50 m / sec while the last of these successive rolls has a peripheral speed of 50-100 or more m / sec. If the polymers require it, these rollers can also be heated to the surface temperature required for hot stretching. In order to avoid that the threads can wind up on one of the pulling rollers, which would make it impossible to deposit the threads behind the rollers, the threads are sucked off the last roller with compressed air operated nozzles.

This makes it possible to produce spunbonded nonwovens, the individual threads of which have textile properties as are customary in the case of textile or technical threads formed from the same polymers. The removal and distribution of the threads from the last of these rollers can be carried out by suction nozzles and / or by electrostatic charging, so that a uniform sheet-like structure is again formed on the depositing belt.

The known spunbonded nonwoven processes with pre-stretching by means of suction nozzles have the disadvantage that considerable pressures of 3 to 20 bar are required for drawing off at high thread speeds in order to give the threads the appropriate speed. Even if you pull the threads from the drawing rollers by means of compressed air-operated suction nozzles, this results in a considerable consumption of compressed air. This compressed air consumption is regarded as an essential cost factor in the production of the spunbonded webs formed in this way.

In the methods described above, it does not matter whether the threads are drawn from many spinnerets arranged in a row, each with a correspondingly high number of spinneret holes, or from one or more long spinnerets with an even division of the spinneret holes or from a plurality of long spinnerets offset with respect to one another, since the take-off nozzles or the electrostatic distribution ensure that the flatest possible structure on the conveyor belt consists of tangled individual threads. However, if you place them on this conveyor belt with compressed air nozzles, there is still the risk that the compressed air jet, together with the threads to be deposited, will hit the belt and cause a more or less irregular confusion of the fleece, which, since a textile structure is as even as possible in the surface should be undesirable.

Placing on the conveyor belt is followed by a customary and known aftertreatment, be it with spraying, drying and / or hot calendering and / or needling and subsequent winding, as is also the case with fabrics and knitted fabrics.

The invention has for its object to avoid the high compressed air consumption and still achieve high take-off speeds from the spinnerets without the risk of winding the threads on a take-off roller.

According to the invention, this is done in that the threads by means of combing themselves before being fed to the moving surface not touching toothed rollers for the purpose of uniform distribution of the threads in the axial direction of the toothed rollers of a corrugation with a simultaneous positive withdrawal of the threads.

The intermeshing but not touching toothed rollers have different effects. Due to the interlocking of the teeth, they bring about the required entrainment effect and thus the safe pulling of the fed threads practically without slippage. In addition, the resulting curl of the threads, due to the interlocking of the teeth, tends to cause the threads to spread evenly along the teeth, the curl causing the threads to spread away from the teeth, thereby allowing the threads to wind up on one of the Tooth rolling is practically excluded.

The pair of intermeshing rollers is able to grasp threads that are supplied with more or less tension from one side, to pull them and on the other side to further convey them in a plane symmetrical to this pair of rollers, without any thread tension on the threads on the conveying side must be exercised. In particular, no compressed air is required at this point. All that is required as energy is the drive of this pair of valens to a desired peripheral speed, which is in a certain ratio to the speed at which the threads are drawn off and deposited.

Due to the elimination of the otherwise necessary compressed air jets, the wide thread band, which is evened out by the intermeshing rollers, is conveyed evenly further and placed on the moving surface. Because of the absence of compressed air jets, no additional confusion can arise. Due to the possible high deduction and laydown the threads lay themselves in curls and loops on the moving surface, thus forming the desired flat structure. The peripheral speeds of the intermeshing rollers are in the range of about 10-120 m / sec, but can also be lower or higher.

Intermeshing, non-contacting toothed rollers have already been used to convey fiber strands combined in the manner of cables. However, the toothed rollers were only used for conveying without the cable-like character of the fiber strands having been changed in any way. In contrast, the present invention is to pull off loosely supplied threads and to ensure a uniform distribution within the amount of these threads, that is to say to exert an effect on the threads in the axial direction of the toothed rollers, which is of no importance in the case of the cable-like bundled fiber strands .

Usually the threads are fed to the toothed rollers as a belt. However, it is also possible to feed the threads to the toothed rollers as a thread chain, which is a more strand-like agglomeration which is then pressed flat apart under the influence of the corrugation by the meshing toothed rollers.

In particular, if threads are involved which, due to their pretreatment, still have a certain adhesiveness, it is expedient to allow a radial air flow to escape between the teeth of the toothed rollers, which then possibly blows away adhesive threads from the teeth of the toothed rollers.

The device for performing the method described above is advantageously designed so that the toothed rollers are provided as hollow rollers with slots provided between the teeth and with air inlet openings on their end faces.

In order to be able to adapt the air flow to the respective operating conditions, the size of the air inlet openings on the end faces of the toothed rollers can be made adjustable.

For reasons of stability, it is advisable to provide several slots in the axial direction with ridges in between for each tooth base. The slots are expediently offset from one another with respect to the slot belonging to the other toothed roller. This results in a continuous airflow around each tooth.

The toothed rollers can also be combined with conventional take-off and stretching rollers, for which purpose one or more optionally heated removal and stretching rollers are provided in front of the toothed rollers.

If the threads are drawn off directly from the spinnerets with these toothed rollers, strength and elongation properties are achieved, as are known from the so-called "pre-oriented" yarns. If the threads are drawn off by the toothed rollers from the last of the successive draw-off and stretching rollers, thread properties can be achieved as with individual fully drawn threads. In the case of several successive draw-off and stretching rolls, all intermediate states can also be combined, for example if one part of the threads from a spinneret is passed over the first of these rolls, another part of the threads from a spinneret over the third of these rolls and another Draws off part of the threads from a spinneret over the fifth of these rollers etc. and has all the threads drawn off and deposited together after the last roller by the pair of toothed rollers. In this form, spunbonded nonwovens made of several polymers can also be combined, for example by pulling threads made of polymer A from the first take-off roller, threads made of polymer B from the third take-off roller, from the fifth take-off roller made of polymer C and so on, and after the last take-off - and drawing roller pulls all threads together through the pair of toothed rollers.

The uniformity of the threads on the moving surface can be further improved by arranging a device for electrostatically charging the threads between the toothed rollers and the moving surface. Because of this charge, the threads then repel each other, which means that they are distributed evenly across the moving surface. In this case, the device is expediently connected on one side to the moving surface, which additionally results in the deposited threads being evened out when the threads are placed on the movable surface.

Exemplary embodiments of the invention are shown in the figures. Show it:

1 is a pair of toothed rollers with threads drawn from this,

2 shows a single toothed roller in section along the line II-II from FIG. 1,

Fig. 3 shows a device in which the threads through Tooth rollers are pulled directly from the spinnerets in a side view,

4 the same device in front view,

5 shows a device with the take-up and drawing rollers upstream of the toothed rollers in a side view,

Fig. 6 shows the same device in front view.

1 shows a pair of toothed rollers with the toothed rollers 1 and 2, in which the teeth 3 of the toothed roller 1 and the teeth 4 of the toothed roller 2 mesh with one another but do not touch. A group of threads 5 lying next to one another is drawn off from the toothed rollers 1 and 2 and are subjected to a corrugation in the region of the meshing of the teeth 3 and 4 in accordance with the meshing of the teeth. In this case, however, the threads 5 are not pinched, but are taken along practically without slip due to the corrugation, which results in the positive withdrawal of the threads 5. The two toothed rollers 1 and 2 rotate in the direction of rotation indicated by the two arrows. On their end faces, the toothed rollers 1 and 2 are closed by end plates 6 and 7, which delimit a cavity 8 in the interior of the toothed rollers 1 and 2, which will be discussed in greater detail in connection with FIG. 2. In each of the end plates 6 and 7, four air passages 9 are let in, which can be opened or closed from inside by sliding covers 10 to a greater or lesser extent. These covers 10 are part of a plate 11, which rests from the inside against the relevant end wall 6 and 7 and is held by screws 13 on the relevant end wall. In order to allow rotation of the plate 11, the End walls 6 and 7 have corresponding elongated holes 12 through which the screws 13 pass. The function of the air passages 9 is discussed in more detail below.

Fig. 2 shows the toothed roller 1 and 2 (both rollers are identical) in section, namely along the line II-II in Fig. 1. The toothed roller 1 and 2 is supported by the shaft 14, by means of the Core 15, which is secured against the skins 14 by means of the wedges 16. The support plates 17 and 18 are welded to the core 15 and at both ends, over the outer circumference of which the basket 19 with the teeth 3 and 4 growing out of it is drawn. The basket 19 is axially secured on the support plates 17 and 18 by the end plates 6 and 7 and on the opposite side by the end plates 6a and 7a (not visible in FIG. 1). For this purpose, the screws 20, 21 are screwed into the end faces of the basket 19 through the end plates 6, 7 and 6a, 7a. The end plates 6, 7 and 6a, 7a protrude beyond the outer edge of the support plates 17 and 18 and hold them in an annular groove.

The basket 19 formed by the tooth bases in each case has axial slots 22 between the teeth 3, 4, so that air or radial air can escape from the interior 8 of each toothed roller 1 or 2.

If the toothed rollers 1 and 2 are set in rotation, with open passages 9, an air flow forms in the end walls 6, 7, 6a, 7a into the interior 8 and out of it through the slots 22, since the toothed rollers 1 and 2 act as a radial fan wheel, which sucks in air centrally and blows radially outwards in the area of the outer circumference. The strength of this flow depends on the one hand on the speed of the Tooth rollers 1 and 2, also from the degree of opening of the air passages 9, which, as explained above in connection with FIG. 1, can be set optionally. Air is sucked in independently of one another through both toothed rollers 1 and 2 and blown out through the slots 22. The air stream exiting through the slots 22 blows the threads 5 away from the teeth after they have left the area of the meshing of the teeth 3 and 4. Since this is done symmetrically, the threads 5 are blown evenly from both sides and can fall down freely.

It should be noted that when processing threads that are hardly sticky in the area of rolls 1 and 2, rolls that do not have slits can also be used. In this case, it is also possible to completely close the passages 9. However, the radial blow-out of air between the teeth 3 and 4 is an effect of particular security against the threads being wound around the rollers, which would immediately interrupt the function of the device in question.

The exit speed of the threads 5 from the pair of rollers 1 and 2 initially corresponds to the peripheral speed of the rollers minus any possible small slip. The speed of the threads 5 is initially maintained after the roller clamping or friction has been released by the inertia, the threads 5 fall down at this speed and can be picked up by a conveyor belt shortly thereafter.

Fig. 3 shows an apparatus for producing spunbonded fabric using the two toothed rollers 1 and 2, which are shown only schematically here. The up in a known manner Built spinning head 23 contains a melt or solution stream from a corresponding source, which is pushed through holes in the spinnerets 24 at a uniform flow rate, whereby the threads 5 are formed. In the blow shaft 25 drawn here with cross-flow cooling, the threads 5 are cooled by the cross-flowing air and thereby solidified. A vibration knot roller 26 ensures that the threads 5 thus formed cannot swing back and forth too much. Arranged under the vibration knot roller 26 is the pair of toothed rollers 1 and 2, which, by combing their teeth, pull the threads 5 from the top of the spinneret 24 and release them downwards so that they fall onto the conveyor belt 27. For better entrainment of the fleece 28 thus formed on the conveyor belt 27, the suction box 29 is arranged below the conveyor belt 27 and sucks the threads 5 or the fleece 28 onto the air-permeable conveyor belt 27 with the vacuum therein. The conveyor belt 27 then conveys the fleece 28 as a flat structure into an aftertreatment section, not described above.

FIG. 4 shows the device according to FIG. 3 in a side view, from which it can be seen that a band of considerable width of threads 5 can be pulled off by the toothed rollers 1 and 2 and placed on the conveyor belt 27. The two dash-dotted lines drawn from top to bottom through the device indicate that the device can also be made wider or narrower.

5 shows a variant of the arrangement according to FIGS. 3 and 4. According to FIG. 5, the draw-off and stretching rollers 30 are connected between the Elass shaft 25 and the two toothed rollers 1 and 2, each of which follows runs at the same or greater peripheral speed than the previous one. The rollers 30 can also be heated to certain polymer-specific temperatures. This allows the threads 5 to be stretched in an adjustable manner, so that the threads released by the last of the rollers 30 obtain the desired tensile strength and other properties. From the last of the rollers 30 running at high peripheral speed, the threads 5 are drawn off by the pair of the two tooth rollers 1 and 2, whereby, as described in relation to FIG. 3, winding of the threads onto one of the tooth rollers 1 and 2 is avoided, so that the threads 5, as described with reference to FIGS. 3 and 4, are placed on the conveyor belt 27 and transported for further processing.

FIG. 6 shows the arrangement according to FIG. 5 in a front view.

5 and 6, a further organ is installed, namely the device 31 for electrostatically charging the threads 5. It is a known high-voltage device by means of which the threads 5 are statically charged so that they are mutually dependent repel. The electrostatic charging of the threads 5 is retained even when passing through the toothed rollers 1 and 2, since in this case their teeth are provided with a sufficiently thick insulation layer. The electrostatic charge then ensures that after leaving the toothed rollers 1 and 2, the threads 5 spread apart, so that they lie on the conveyor belt 27 with a substantially greater width than the width of the thread belt in the region of the toothed rollers 1 and 2. On the one hand, the density of the Fleece reduced on the conveyor belt 27, on the other hand, there is also a particularly uniform distribution of the individual threads on the conveyor belt 27.

It should also be pointed out that the device 31 for electrostatic charging can also be attached to the arrangement according to FIGS. 3 and 4.

As clearly shown in FIG. 6, in the arrangement in question a band of threads 5 is extruded from the spinneret 24 which is relatively narrow. Accordingly, the blow chute 25 and the following devices, namely the vibration knot roller 26, the draw-off and stretching rollers 30 and the toothed rollers 1 and 2 can also be designed to be correspondingly narrow. The broadening of the band formed by the threads 5 can also take place after the toothed rollers 1 and 2, since the device for electrostatic charging can be arranged as device 31 'after the toothed rollers 1 and 2, so that the electrostatic charging can have a full effect here , because there are no longer any pulling forces on the threads after the toothed rollers 1 and 2.

Claims

Patent claims

1. A process for the production of spunbonded nonwoven from synthetic polymers, in which the threads forming the spunbonded nonwoven after spinning and cooling as a wide thread chain on a moving surface, e.g. in the manner of a conveyor belt, characterized in that before being fed to the moving surface (27) the threads (5) by means of intermeshing, non-contacting toothed rollers (1, 2) for the purpose of uniform distribution of the threads (5) in the axial direction of the toothed rollers (1, 2) a corrugation with simultaneous positive withdrawal of the threads (5) are subjected.

2. The method according to claim 1, characterized in that the threads (5) are fed to the toothed rollers (1, 2) as a belt.

3. The method according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the threads (5) to the toothed rollers (1, 2) are fed as a thread chain.

4. The method according to any one of claims 1 to 3, that a radial air flow exits between the teeth (3, 4) of the toothed rollers (1, 2).

5. Device for carrying out the method according to one of claims 1 to 4, characterized in that the toothed rollers (6, 7) as hollow rollers with between the teeth (3, 4) provided slots (22) and on their end faces with air passages (9 ) are provided.

6. The device according to claim 5, d a d u r c h g e k e n n z e i c h n e t that the air passages (9) are adjustable in size.

7. Apparatus according to claim 5 or 6, d a d u r c h g e k e n n z e i c h n e t that several slots (22) are provided in the axial direction with intermediate webs per tooth base.

8. Device according to one of claims 5 to 7, characterized in that the slots (22) are offset from one another with respect to the slot belonging to the other toothed roller.

9. Device according to one of claims 5 to 8, d a d u r c h g e k e n z e i c h n e t that one or more optionally heated draw-off and stretching rollers (30) are provided in front of the toothed rollers (1, 2).

10. Device according to one of claims 1 to 9, d a d u r c h g e k e n n z e i c h n e t that a device (10) for electrostatic charging of the threads is arranged in front of the toothed rollers (1, 2) and the moving surface (27).

11. The device according to claim 10, d a d u r c h g e k e n n z e i c h n e t that the device (10) one-sided on the moving surface

(27) is connected.