DE60014900T2 - DEVICE FOR MANUFACTURING A FIBER TRAY AND METHOD FOR CARRYING OUT THIS DEVICE - Google Patents

Abstract

The invention concerns an installation comprising at least an extruder (1) for a melted organic polymer feeding a die (2) for producing a curtain of filaments (3); a cooling zone (4) for providing at least surface solidification of said extruded filaments; a suction device (5) in the form of a narrow chamber with rectangular cross-section, wherein the curtain of filaments is subjected to the action of high speed air streams causing the filaments to be drawn; means (6) for deflecting and slowing down the air flow at the outlet of the drawing slot and for distributing the filaments homogeneously on a receiving belt (7). The invention is characterised in that the means for producing the different operational phases, namely the extruding means, the cooling means, the filament drawing assembly and the distributing means, are separate from one another and can be individually adjusted, not only based on the production to be obtained (type of polymers, elementary yarn count of the filaments produced, weight per unit area of the web produced), but also at the beginning of production.

Description

technical area

The The present invention relates to an improved device for Production of a nonwoven web, commonly under the original Name "Spunbond" is known and formed by continuous synthetic filaments.

she also concerns a method for the use of such a device.

State of technology

• – ein geschmolzenes organisches Polymer durch eine Ziehdüse, die mit Löchern durchbohrt ist, zu extrudieren, um ein Bündel oder eine Bahn von Filamenten zu bilden;
• – dann die extrudierten Filamente durch Ziehen mittels einer oder mehrerer Vorrichtungen mit Fluidstrahl, insbesondere mit Druckluft, auszurichten,
• – und schließlich das Filamentbündel in Form einer Bahn auf einem beweglichen Förderband aufzunehmen, das im Allgemeinen einer Ansaugquelle unterworfen ist und dessen Geschwindigkeit in Abhängigkeit von den Merkmalen der Bahn, insbesondere der Flächenmasse, die erzielt werden sollen, eingestellt ist.

The production of nonwoven webs of the "spunbond" type dates back decades and generally consists of:

• Extruding a molten organic polymer through a die pierced with holes to form a bundle or web of filaments;
• Then align the extruded filaments by drawing with one or more fluid jet devices, in particular compressed air,
• And finally to receive the filament bundle in the form of a web on a moving conveyor belt which is generally subjected to a suction source and whose speed is set in dependence on the characteristics of the web, in particular the basis weight which is to be achieved.

To In production, the web is solidified by, for example, a Calibration or calendering, preferably in the hot state, is made so that the elementary filaments with each other get connected.

Further Solidification treatments can also carried out be such as a needle treatment (conventional or by fluid jet), and / or the application of a binder the surface or in the interior of the train.

numerous proposals were made to make such tracks, all to the destination have one as possible homogeneous web or as homogeneous as possible Voile with a high productivity and more and more with elementary Filaments of great fineness with a titer of less than 2 dtex is.

Among the oldest documents that make it possible to produce such webs, the patent GB-A-932 482 in which the filaments run in fresh air after extrusion, leaving the die at a sufficient distance to permit at least surface consolidation of the extruded filaments before being introduced into the interior of a suction and die nozzle which causes the formation of a ring air flow at high speed.

Around the scattering of the filament bundle to achieve this is an electrostatic charge caused by an electrostatic charge Generator can be obtained, which has an effect of the type Corona causes the upstream or downstream to suction nozzle is localized.

Under the different parameters used for the production of webs with good quality considered Need to become, have to in dependence of the extruded polymers the distance between the exit of the die and the entrance to the interior of the drawing system, the speed of the Air inside the nozzle and also the exit velocity of the filaments from the latter be adjusted so that the support on the recording tape is done regularly.

To solve this problem of the homogeneity of the support on the conveyor belt, was in the patent US-A-3,286,896 proposed to carry out the suction device in the form of a chamber of rectangular cross-section, small width and long length, such unit at the entrance of a suction chamber for the extruded filaments, followed by an additional chamber, is injected into the air at low pressure, and of a Long-length channel in which the air flows at high speed includes. In order to achieve a good distribution of the filaments on the receiving surface, a deflection unit, which slows the air flow, arranged at the exit of the drawing chamber, whereby a better distribution of the filaments is possible.

Such systems, in which the filaments pass through inside a suction and pulling chamber of rectangular shape, which may possibly have the width of a web of extruded filaments, have been proposed, in particular from the French patent 2 064 087 (according to the patent US-A-3,802,817 ), the web of filaments being exposed on both sides to the action of high velocity air streams causing it to be pulled.

Moreover, the patent describes US-A-4 064 605 an improvement to such a technique, which is to provide an additional cooling unit for the filaments prior to insertion into the actual draw chamber, exposing the bundle of filaments to a transverse airflow.

Finally, the advancement of technology has led to the manufacture of equipment in which the filaments are drawn at the exit of the die and conveyed on a take-up belt, any passage of the filaments in the fresh air at the exit of the die being omitted by means of an integrated unit it makes it possible to carry out the cooling, the drawing and the support of the filaments on the conveyor belt, in particular from the patent U.S. 4,627,811 as well as out US 5,814,349 evident.

A such execution a facility allows it to obtain nonwoven webs that are of a low basis weight and a good regularity are, however, complex and delicate in use.

moreover lack of flexibility in these facilities, as it is not possible the cooling conditions at the exit of the drawing nozzle easy to adjust, depending on of the polymers and the titer of the filaments that are produced should vary, and the final characteristics of the web.

Further such facilities are bad for adapted the production of filaments with great fineness.

So To date, no satisfactory solution has been proposed Plant for the production of spunbond fiber fleece, which makes it possible a high productivity when the filaments are fine, i. a titer below 2 dtex, which requires a perfect and extremely regular pulling the filaments without breaking the same takes place during this drawing phase.

Now, to achieve high production, i. a high throughput of polymers at the exit of the die, on the one hand, it is necessary that the pulling speed is increased in the drawing slot, thus resulting in a greater air flow, coupled with a relatively high temperature of the filaments before drawing leads, give them a certain plasticity to preserve.

moreover implies a pulling of the filaments, coupled with a high productivity, too advance that the airflows can be braked at the exit of the drawing slot to a regular edition the filaments on the recording tape and the production of a voile of good quality to achieve.

statement the invention

It was now, which is also the subject of the invention, a new type of plant developed, which is the production of nonwoven webs of continuous synthetic filaments allows and a solution for all represents the aforementioned problems.

All in general, the plant according to the invention of the type defined in claim 1.

thanks such an embodiment, which is directed against the technical advancement in this area is a progression that tended to be completely integrated Units for the cooling, the drawing and distribution of the filaments on the conveyor it was found that such a separation of the different operating phases of each other a very large number offers advantages, in particular as regards the flexibility of use and the possibility the much simpler setting of production depending on from the tiers of the threads and the weight of the web to be produced.

• – sind die Kühlzone am Ausgang der Ziehdüse und die Ziehzone für die Filamente von einer Vielzahl von nebeneinander in Abhängigkeit von der Produktionsbreite angeordneten Elementarmodulen gebildet, wobei das Öffnungssystem der Filamente seinerseits von einer Einheit gebildet ist, die sich über die gesamte Breite der erzeugten Bahn erstreckt;
• – wird die Kühlung am Ausgang der Ziehdüse mit Hilfe einer Einheit erzielt, die mehrere aufeinander folgende Zonen umfasst, die es ermöglichen, den Vorhang von Filamenten einem quer verlaufenden Luftstrom zu unterziehen, dessen Geschwindigkeit und Temperatur in jeder der Zonen unabhängig eingestellt werden können;
• – ist das Öffnungssystem der Filamente, das vom Ausgang des Ziehsystems entfernt angeordnet ist, von einer Einheit gebildet, die den Luftstrom seitlich ablenkt und die Geschwindigkeit desselben und jene der Filamente verringert und das gleichmäßige Auflegen auf das Förderband erleichtert, indem zum Zeitpunkt dieses Auflegens jedes Zurückschnellen beseitigt wird; ist vorzugsweise das Öffnungssystem der Filamente auch mit einer Einheit verbunden, die die Filamente vor ihrem Auflegen auf das Aufnahmeband elektrostatisch auflädt und entweder unmittelbar am Ausgang des Öffnungssystems angeordnet oder in dieses integriert sein kann;
• – umfasst die Anlage Computerkontrollmittel für die Gesamtheit der Untereinheiten, die es ermöglichen, automatisch die Erhöhung der Geschwindigkeit der Produktionsanlage durchzuführen.

Preferably, in practice and according to the invention:

• - The cooling zone at the exit of the die and the drawing zone for the filaments of a plurality of juxtaposed depending on the production width elementary modules are formed, wherein the opening system of the filaments in turn is formed by a unit which extends over the entire width of the produced web ;
• The cooling at the outlet of the die is achieved by means of a unit comprising a plurality of successive zones making it possible to subject the curtain of filaments to a transverse flow of air whose speed and temperature in each of the zones can be adjusted independently;
• The opening system of the filaments located away from the exit of the drawing system is constituted by a unit which laterally deflects and reduces the velocity of the air stream and facilitates its uniform application to the conveyor belt at the time of this laying Snapback is eliminated; Preferably, the opening system of the filaments is also connected to a unit that electrostatically charges the filaments prior to their placement on the receiving tape and can either be located directly at the outlet of the opening system or integrated into this;
• - The system includes computer control means for the set of subunits, which make it possible to automatically increase the speed of the production plant.

• – während der Startphase die Temperatur der Luft innerhalb jeder Kühlzone von einer Zone zur nächsten abnimmt, wobei die Geschwindigkeit der in jeder Zone durchströmenden Luft einstellbar ist und zwischen 0,5 m/Sekunde und 3 m/Sekunde in jeder der Zonen betragen kann, wobei der Ziehschlitz in entfernter Position gehalten wird,
• – dann nach und nach die Produktionsgeschwindigkeit erhöht wird, wobei die Parameter der Kühlzone und der Temperaturerhöhung der Filamente verändert werden, um:
• • die Luftgeschwindigkeit der ersten Zone zu erhöhen, wobei die Temperatur unverändert bleibt,
• • die Temperatur der zweiten Zone zu erhöhen, um sie auf das Niveau jener der ersten Zone zu bringen und die Luftgeschwindigkeit dieser Zone zu erhöhen,
• • die Lufttemperatur der dritten Zone und die Luftgeschwindigkeit dieser Zone zu erhöhen;
• – gleichzeitig nach und nach die Breite des Ziehschlitzes verringert wird, um einen Funktionsnennwert zu erreichen, wobei der Ziehluftdruck nach und nach erhöht wird.

The invention also relates to a method for using such a device, this method being characterized in that:

• During the starting phase, the temperature of the air within each cooling zone decreases from one zone to the next, the velocity of the air flowing through each zone being adjustable and being between 0.5 m / s and 3 m / s in each of the zones the drawing slot is kept in a remote position,
• - then gradually increase the production rate, the parameters of the cooling zone and the temperature increase of the filaments are changed to:
• • to increase the air velocity of the first zone, keeping the temperature unchanged,
• Increase the temperature of the second zone to bring it up to the level of that of the first zone and increase the air velocity of that zone,
• • increase the air temperature of the third zone and the air velocity of this zone;
• - At the same time gradually the width of the drawing slot is reduced in order to achieve a Funktionsnennwert, wherein the drawing air pressure is gradually increased.

It It should be noted that in the inventive method, the temperature the air inside each cooling zone generally in a range that can go from 5 ° C to 60 ° C.

Summary Description of the drawings

The Invention and the benefits that result from it, are with Help of the following embodiment, which has indicative but non-limiting character and through the accompanying diagrams are shown, better understood, in which:

1 an overall view of a device according to the invention is;

2 a schematic detail view of the cooling unit or more precisely the unit for controlling the temperature of the filaments before insertion into the actual drawing slot;

3 is a schematic view illustrating the general structure of a drawing slot.

realization the invention

With reference to the attached 1 Thus, the device according to the invention essentially consists of at least one extruder, which is identified by the general reference symbol (FIG. 1 ) and a die ( 2 ), which involves the formation of a curtain of filaments ( 3 ) and is supplied with synthetic polymer such as polyamide, polyethylene, polyester, etc.

Out Practical view, the drawing nozzle for example, from a perforated plate with 5000 holes per Meter width formed with a diameter of, for example, 0.5 mm be. These holes are on a large number of parallel rows, for example eighteen Rows, over a width at the exit of the die distributed by 140 mm.

At the exit of this die is the cooling unit ( 4 ), which makes it possible to adjust the temperature of the filaments as a function of the polymer and according to the invention consists of three successive zones ( 4a . 4b . 4c ), which make it possible to open the curtain of filaments ( 3 ) flow through the air streams whose speed and temperature can be adjusted.

For example, the length of this cooling zone is about 1200 mm and the temperature and velocity of each of the zones are from the first zone (FIG. 4a ) to the third zone ( 4c ) decreasing.

The Temperature of the air in this zone is generally between 15 and 60 ° C, in turn, the velocity of the air flowing through between 0.5 m / s and 3 m / s.

Downstream to this cooling zone is the actual drawing unit ( 5 ), which is in the form of a closed space, comprising a slot ( 6 ), inside which air is injected under a pressure of 0.5 to 1.5 bar.

In general terms, such a drawing system may be similar to the teachings of FR 1 582 147 or GB 932 482 ( 3 ), which makes it possible to achieve the suction of the curtain of filaments and its drive by high-speed air flows, which make it possible to perform a drawing.

How out 3 in which such a drawing unit ( 5 ) is shown schematically, this essentially consists of an actual drawing slot ( 10 ), whereby the of a collector ( 11 ) incoming air into the interior of this chamber ( 10 ) through a distributor ( 12 ) and an acceleration chamber ( 13 ) is introduced.

However, such a suction / draw unit is preferably designed such that the width (F) of the slot ( 10 ) can be changed during the operation of the plant, whereby it is on the one hand possible to adjust the flow rate of the air streams and thus the titer to be obtained, and on the other hand, the starting process is facilitated, as in the following description se hen is.

in the Generally, filaments are produced with a titer between 1.5 dtx and 3 dtx the width (F) of the slot between 3 mm and 10 mm, whereby this distance of the slit to 25 mm during the Starting phase can be brought.

At the exit of the draw unit ( 5 ) the filament bundle ( 3 ) on the conveyor belt ( 7 ) not projected directly, like this FR 2 064 087 or US 4,064,605 but one unit ( 6 ), which is a distraction of the out of the slot ( 5 ), and a slowing down of this jet of air, resulting in the opening of the curtain of filaments and the distribution of these latter on the conveyor belt ( 7 ) leads.

A such unit may, for example, in the form of a slot with diverging Walls available be.

In order to further enhance the scattering of the curtain of filaments and the random distribution on the receiving surface, the latter can be electrostatically electrostatic with the help of a system of the type "corona", which with the distribution element ( 6 ) are charged electrostatically, similar to the teachings of the British patent 932 482 ,

Optionally, the means which allow electrostatic charging of the filaments may be provided at the entrance of the divergent walls of the distribution element (FIG. 6 ) be integrated.

example of use

On a plant of the type shown in the accompanying figures, a nonwoven web is formed consisting of continuous polypropylene filaments, in this case 38 MSR. The polymer is melted in a five-melt extruder, and at the exit of the extruder, it is filtered on a filter composed of stainless steel mesh before being fed into the actual die ( 2 ) is introduced.

For this purpose, the machine comprises two drawing nozzles ( 1 ), which are arranged in series and each comprise 5000 holes with 0.5 mm diameter per meter width.

Moreover, according to the invention, the cooling zone ( 4 ) and the drawing zone ( 5 ) preferably formed from a plurality of elementary modules, each having a width of 50 cm.

The distribution element ( 6 ), at the exit of the drawing zone ( 5 ), in turn has a continuous slot which extends over the entire width of the plant and has the shape of a spreading element whose width is 15 mm with respect to the exit zone of the filaments of the slot (FIG. 5 ) and 100 mm opposite the conveyor belt ( 7 ) having.

The distribution unit ( 6 ) may possibly be associated with additional means which also allow to charge the filaments electrostatically, whereby the scattering of the bundle and its distribution on the conveyor belt ( 7 ) be improved.

Of the Start of the line is done with low production with a polymer throughput, which is set to 0.2 g / mm and per hole.

• - Zone (4a)
• • Lufttemperatur: 35°C
• • Luftgeschwindigkeit: 1 m/Sekunde – Zone (4b)
• • Lufttemperatur: 20°C
• • Luftgeschwindigkeit: 1 m/Sekunde
• – Zone (4c)
• • Lufttemperatur: 15°C
• • Luftgeschwindigkeit: 0,5 m/Sekunde.

During this starting phase, the following parameters are observed in the temperature control zone, with a cooling zone ( 4 ), the three consecutive zones ( 4a . 4b . 4c ), which have a total length of about 1200 mm, during which the extruded filament bundle ( 3 ) is exposed to a flowing air stream coming from each of these zones under the following conditions:

• - Zone ( 4a )
• • Air temperature: 35 ° C
• • Air speed: 1 m / second - Zone ( 4b )
• • Air temperature: 20 ° C
• • Air speed: 1 m / second
• - Zone ( 4c )
• • Air temperature: 15 ° C
• • Air speed: 0.5 m / second.

During this start cooling phase, the width (F) of the draw slot ( 5 ) is set to 25 mm, the pressure of the air injected into the slot being 0.3 bar.

The drawn beam runs at the exit of the drawing slot ( 5 ) into the system ( 6 ) for opening and distributing the jet having diverging shape, with a width at the entrance of 10 mm and an opening at the base of approximately 100 mm.

During this entire start-up period, the polymer is deposited on a conveyor belt ( 7 ) with the help of a "leader" that is unrolled on the tape and prevents it from clogging drops of molten polymer.

If a uniform Throughput of polymer produced in the die, the production speed the line gradually increased.

• – Erhöhung der Geschwindigkeit der Luft der ersten Zone (4a) auf 1,5 Meter/Sekunde, wobei die Temperatur unverändert bleibt;
• – Erhöhung der Temperatur der Luft der zweiten Zone (4b), die auf 30°C erhöht wird, wobei ihre Geschwindigkeit auf 1,3 Meter/Sekunde erhöht wird;
• – Erhöhung der Temperatur der Luft der dritten Zone (4c) auf 20°C und Erhöhung der Geschwindigkeit, die auf 1 Meter/Sekunde erhöht wird.

During this entire period of speed increase, the parameters of the Cooling ( 4 ) and temperature control zone of the filaments gradually changed, namely:

• Increasing the velocity of the first zone air ( 4a ) at 1.5 meters / second, the temperature remains unchanged;
• Increasing the temperature of the air of the second zone ( 4b ), which is raised to 30 ° C, increasing its speed to 1.3 meters / second;
• - raising the temperature of the air of the third zone ( 4c ) to 20 ° C and increase the speed, which is increased to 1 meter / second.

Such a procedure makes it possible to ensure the at least superficial solidification of the extruded filaments, which do not stick together when they enter the drawing slot (FIG. 5 ).

What this drawing slot ( 5 ), its width is gradually reduced from 25 mm to 5 mm throughout the start-up phase, and at the same time, the pressure of the drawing air is gradually increased from 0.3 to 1 bar approximately.

The Temperature of the drawing air is controlled and remains during this entire period constant.

thanks Such an approach, it is possible on a plant, at the different zones remain stationary, polymers produce different nature and also the production of To simplify filaments that have a very fine denier of about 1.7 dtex or even less.

The fact that the temperature of the last two cooling zones ( 4b ) and ( 4c That is, as the air used in the process is gradually increased, it makes it possible to increase the plasticity of the polymer and thus facilitates its drawing, allowing greater fineness of the filaments.

Finally, it allows the fact that while the operation of both the pressure of the drawing air and the width of the Pull slot can be adjusted, the drawing conditions optimize, which of course by obtaining a high production in connection with the production of very fine filaments.

The structure of the filament opening system, located downstream of and independent from the drawing system, also promotes regular and homogeneous support of the filaments on the receiving surface (US Pat. 7 ).

Namely, the production of filaments having very fine titers is accompanied by a high speed, about 5000 m / min of the filaments at the exit of the drawing slot. The apparatus used in the plant according to the invention ( 6 ) allows slowing down the speed of the filaments as well as the air flow exiting the drawing slot and promotes their distribution on the conveyor belt by the fact that it eliminates the phenomena of recoil that can interfere with regular and homogeneous support.

The Whole unit settings are made and are automatic controlled by a "process" computer, which after the principle of "fuzzy logic "works and it allows a variety of independent To take into account parameters.

The concrete previously stated Example possible it to obtain filaments that have a titer of 1.7 dtex with a Polymer throughput of 0.65 g / hole / minute have.

The obtained voiles can weigh 10 to 150 g / m ² , are very regular and can be used for various applications, such as hygiene products (diapers for babies), products for medical or industrial use.

If it also makes such a facility possible It is of course also possible to obtain filaments with very fine titers Production of the line increase significantly when the titer of filaments elevated becomes.

If For example, in the previous example filaments with a Titers were made of 2 dtex, so the polymer throughput would have increased to 0.8 g / hole / minute can be.

Claims (7)

Device for producing a nonwoven web, comprising: - at least one extruder ( 1 ) for a molten organic polymer with which a die ( 2 ), which allows a curtain of filaments ( 3 ) to create; - a cooling zone ( 4 ), which makes it possible to achieve the at least superficial solidification of the extruded filaments; A pulling device ( 5 ) which is in the form of a chamber of rectangular cross-section and drawing slot (F) and of small width, in which the curtain of filaments is subjected to the action of air streams at high speed, thereby causing the drawing of the filaments; - Medium ( 6 ), which make it possible to divert the airflow at the exit of the drawing slot and ver slow and the filaments homogeneous on a recording tape ( 7 ) to distribute; in which the extrusion means, the cooling means, the filament drawing device and the distribution means have control means independent of each other, characterized by means for adjusting the width of the drawing slot (F). Device according to claim 1, characterized in that the cooling zone ( 4 ) at the exit of the die and the drawing zone ( 5 ) are formed for the filaments of a plurality of juxtaposed depending on the production width elementary modules, wherein the opening system of the filaments in turn is formed by a unit which extends over the entire width of the produced web. Device according to one of claims 1 and 2, characterized in that the cooling of the output of the die ( 2 ) with the help of a unit ( 4 ), which has several successive zones ( 4a . 4b . 4c ), which make it possible to subject the curtain of filaments to a transverse flow of air whose speed and temperature in each of the zones can be adjusted independently. Device according to one of claims 1 to 3, characterized in that the opening system ( 6 ) of the filaments, which is arranged away from the exit of the drawing system, is formed by a unit which deflects the air flow laterally and reduces the speed of the same and that of the filaments and uniformly placed on the conveyor belt (FIG. 7 ) by eliminating any snap back at the time of this application. Device according to claim 4, characterized in that the opening system ( 6 ) of the filaments is connected to a unit that electrostatically charges the filaments before placing them on the receiving tape. Device according to one of claims 1 to 5, characterized that they are computer control agents for the entirety of the subunits includes that make it possible automatically the increase to perform the speed of the production plant. Method for using a device according to one of Claims 3 to 6, characterized in that: during the starting phase, the temperature of the air within each cooling zone ( 4a . 4b . 4c ) decreases from one zone to the next, the velocity of the air flowing through each zone being adjustable and being between 0.5 m / s and 3 m / s in each of the zones, the drawing slit being kept in a remote position, then gradually increase the production rate, the parameters of the cooling zone and the temperature increase ( 4 ) of the filaments to: • the air velocity of the first zone ( 4a ), the temperature remains unchanged, • the temperature of the second zone ( 4b ) to bring it to the level of that of the first zone and to increase the air velocity of this zone, • the air temperature of the third zone ( 4c ) and to increase the air velocity of this zone, - at the same time gradually reduces the width of the drawing slot in order to achieve a Funktionsnennwert, wherein the drawing air pressure is gradually increased.