DE2146266A1 - Tubular film - with short distance between squeeze and stretching rollers - Google Patents

Abstract

Designed to produce strip material for weaving and other textile machinery applications, polypropylene or low-pressure polyethylene is extruded in tubular form, cooled and then in passing a short distance between squeeze and stretching rollers is raised to stretching temp. The gap between squeeze and stretching rollers is up to twice the dia. of the squeeze rollers. pref. less than the dia. prevents undesired crystalline structures developing and gives a compact equipment.

Description

Process and device for the continuous production of textile film The proposal relates to an apparatus for producing longitudinally stretched blown films ftl for textile processing, the longitudinal stretching of the hose with a Set of mostly free-running rollers immediately after the formation of the tubular bubble, i.e. immediately after it has cooled down below the welding temperature or in the softening or crystallite melting area in one operation and in one heat with this Device is carried out. So the proposal also concerns a procedure.

As is well known, a development has taken place in recent years in the increasingly large number of polypropylene tapes and film blanks, especially made of polyolefins, Stretched monoaxially in the longitudinal direction and processed on weaving machines in the textile sector will.

For the production of these stretched tapes different Devices and techniques were introduced that were more or less successful also in can be applied in practice.

An extremely comprehensive presentation of the technical status for production and processing of these drawn threads and bonder is given by H. Peuker in 'tZeitschrift für die eesarite TEXTILINDUSTRIE ", 11 (1968) pp. 774-782; 12, 5 b67-d'74; 1 (1969) Pp. 10-20; 2 (p.82-88).

In general, the tapes and tapes to be drawn are used here cut from foils, in the hot air duct in one or more godet stretchers Stretched in the longitudinal direction, possibly heat-set, on appropriate winding heads wound up and fed to the loom in a subsequent operation. Here the production from the extrusion to the coiled tapes takes place in one Operation, with either wide slot films or tubular films can be assumed.

More recently, the technology has expanded to that no longer the tapes are stretched, but optionally also the corresponding ones Films from which the ribbons are then cut after longitudinal stretching can.

The advantage is that the stretched film in the form of the wound Roll hung directly on the loom, cut into ribbons or ribbons and straight is fed to the weaving process. This eliminates the winding step of ribbons and ribbons on spools.

For this emerging technology, too, have already been first, different techniques developed from each other, but still today can not satisfy, as they all have disadvantages.

A known method uses flat films for stretching, which can be produced according to the tubular film or flat film process. These films after they have cooled down and travel a relatively long way have fed to a stretching device in which the stretching within a single Horizontal gap is carried out.

This process has a number of serious disadvantages.

First of all, the film produced must cover the long distance mentioned, on which it cools down relatively slowly, strongly crystallized and before enema must be reheated in the stretching device. This crystalline prehistory The film is fundamentally disadvantageous for its stretching, especially since this stretching is carried out compulsorily and in an extremely short stretching gap. The slide must i.e. in fractions of a second, i.e. with expansion speeds of thousands% / sec. are stretched, which is why frequent breaks in the film are the result.

Especially at high running speeds, high degrees of stretching and relatively small final thicknesses of the stretched films are these demolitions unavoidable foils. In addition, this method uses the short one Stretch nip the very high frictional heat of the o film occurring in the stretch nip 20 to 30 C and more, which leads to softening and breaking of the film in the stretching gap.

In order to circumvent this difficulty, the production speed must again significantly reduced and the temperature of the incoming film significantly, i.e. below the area of the crystallite melting point can be lowered.

The latter measure, however, affects the inclination of the stretched strips and ribbons for longitudinal splicing very strong as a result of cold stretching, a property which is disadvantageous for woven ribbon.

Another system has become known, after the blown film with be extruded upwards in a rotating extruder, cooled, squeezed off, deflected, cut open or unfolded and introduced into a stretching device will. This system tries to keep the foil as free as possible without "freezing tensions" to be fed to the drafting system. However, the above system cannot do this solve, as the film must be cooled down to the extent that it can withstand the stresses and strains required when guiding the film, i.e. when deflecting, transporting it on a relative can withstand a long journey and especially when it is cut open and unfolded. this however, means that the film is up to the solid state cooled down and heated again to stretching temperatures before the actual longitudinal stretching must, what the several large heating rollers with a diameter of approx.

Confirm 360 mm before the actual stretching.

The temperature control and the film guide on this system can therefore do not avoid that the film also becomes a crystalline one before it is stretched Has a history, similar to the system described above and above, those of the subsequent stretching and the properties of the stretched film is very detrimental. All the more so, as this system as well as the ones ahead and further The system described above also works with only one stretching gap. These The stretching concept therefore also has the disadvantages already described above, i.e. there are frequent breaks in the film, - which is caused by the attached in front of the stretching device Auxiliary winding device is impressively confirmed - the film tends to the side Stepping in in the stretching gap - which is due to the action of elaborate electrostatic Discharges on the film to be stretched should be prevented - and last but not least is based on the comparable conditions also described above a film with similar disadvantageous properties of increased longitudinal splice received that are not ideally suited for the intended use of weaving machines is.

Another system uses a slot die to extrude a Flat film Immediately after exiting the nozzle, it leads it to a cooling system connected one behind the other and driven rollers of very small diameter, after which they are repeated several times Deflecting is fed to a longitudinal stretching roller system and is stretched ings. This plant has for the first time the advantage of being able to cool the Foil after its exit from the flat nozzle a foil with or without a defined To be able to produce crystallization. Unfortunately, this facility is limited to that Production, i.e. on materials that are very easy flowing and melt indices possess with values of approx. MI / 5/190 = 10 - 20 and above.

However, because of their lower molecular weight, these flat films have compared to blown films, which have melt indices of MI / S / 190 = approx. 0.5 - 1.5, significantly lower mechanical properties, even more prone to splicing and have therefore opted for the production of split fibers and not at all proven for stretched, non-splicing tapes with high mechanical properties. The processing of blown film materials on the named system is not possible, because the flat film emerging from the slot nozzle when it is withdrawn from the nozzle between due to this and the first take-off roller even at low speeds the toughness of the material tears off.

These three exemplary embodiments described are essentially the state of the art is clear when it comes to systems for the production of stretched woven films there is talk of textile ribbons. Other versions are either not related, discontinuously working sub-units, such as film units or stretching devices different designs or systems, in principle with one of the above three examples are technologically comparable or identical.

A device for the production of Baasfolien, which is still in the status nascendi, i.e. before a molecular, ki istalli? en or other taking place Elentation or aging of a stretching on an optimally suitable device can be fed and directly subjected to is not known to this day and has so far been due to blown film technology - in contrast to flat film technology - not considered in the technically possible.

The present proposal poses and solves this task.

The solution to the problem is the design of a device aie partly b # r: annte elements used, combined with new knowledge, and n classifies an experience that is optimal for the purpose in a meaningful and advantageous manner.

The main characteristic of the proposed device is here a construction that enables the blown film immediately after its manufacture to cool with suitable means in the shortest possible way and immediately afterwards and without significant 'change of direction and path after passing the pair of squeeze rollers in the largely amorphous or defined state of order, the set of rollers of the stretching section to feed.

It is very important that the, for example, slightly below its welding temperature cooled film after direct feeding and Leaving the pair of squeeze rollers is immediately fed to the tail rolling mill, wherein the distance between the film pinch and the contact of the film with the 1st stretching roller, i.e. the free path of the film between the pair of squeezing rollers and the stretching section, is kept minimally short.

In general, this distance is about 1 to 2 D of the nip rollers, but preferably less than 1 D.

With nip roller diameters of, for example, 300 mm free path lengths to minimize dwell time and crystallization of the film from about c5 to 35 cm proved to be suitable, but preferably shorter path lengths.

With the help of this constructive solution arise during manufacture of 'leYtil- and other monoaxially stretched Foils with suitable, optimal and, with regard to your inner order, specific properties dwell times of the film between the 1st pair of squeezing rollers and the entry into the roller stretching section from less than 10 to 15 seconds, preferably from less than 6 to 9 seconds.

up has to achieve an amorphous starting film, which maximum Prerequisite for the monoaxial stretching to form a textile or Raschel film With optimal properties, the film has proven itself immediately after formation to quickly deter her plastic bladder, possibly

with a calibrated cooling tube and / or cooling mandrel, to temperatures in which the film is no longer welded due to the squeezing off, preferably to temperatures of the crystalline melting range of the foils, i.e. to temperatures in which there are essentially no crystallites during the short residence times form or at temperatures at which the rate of their formation is already is frozen and is at least slower than the dwell time of the film when passing the free path between the pair of squeeze rollers and the stretching rollers is equivalent to. In the latter case, the temperature of the film is generally low below the intended stretching temperature, which occurs at slow stretching speeds can be corrected by the slightly higher set temperatures of the forging rollers can, which is ater the other way around at holmen stretching speeds in advantageously automatically through the development of frictional heat during stretching of the film corrected, whereby in both cases the crystallization of the film before and during stretching due to the extremely short residence times of the wclie at stretching temperatures is largely excluded within the proposed device.

Again, it is advantageous that the stretching does not focus on one single stretching gap must concentrate, but on the system of forging rollers can distribute, so that the developing frictional heat is also distributed over several Forging rolls transfers, causing local overheating and associated frequent Foil breaks avoided, but also extremely high production speeds maximum high stretching ratios are made possible in an advantageous manner.

Another very important advantage of the proposed device is that the path between the extruder nozzle and the pair of squeegees is dependent on the heat potential of the plastic tubular film to be dissipated, or as a function of it of film thickness, film width, cooling intensity and extrusion speed as required varies and as short as to achieve an optimally suitable one for the stretching Foil can be adjusted as required.

Prerequisite for the development and fulfillment of this beneficial However, technology was, among other things, the surprising one Finding that with the proposed device not only a largely cold, sliced one and in addition separate film can be stretched, which is a cumbersome Fithrung and lengthening the path of this film or its dwell time would have meant, but that even unexpectedly the untrimmed, treated as proposed and about the device guided film tube with the achievement of the shortest dwell times and the greatest property advantages can be stretched.

The following description shows the advantages of the proposed one Device based on an exemplary embodiment on; the following test examples explain the proposed procedure.

However, both the device and the method are in the sense of the proposal can be modified and with the help of professional considerations for the various applications and possible uses.

A preferred embodiment of the proposed device is Figure 1 shows: 2 extrusion systems (1a; 1b), which have a common blow head (3) with a cooling ring and each have a filling funnel (2a; 2b) mounted on a bogie (5).

The bogie (5) rotates around its axis of symmetry, so that the through the tube (4) produced by extrusion also rotates, to avoid unequal Foil wrap.

The extrusion systems (la; ib) and the bogie (5) are on one stable profile welded construction (6) mounted, which upwards as required or down is adjustable depending on the wall thickness and diameter of the Hose, as well as the desired one, depending on its extrusion speed and the required temperature of the hose before it enters the first pair of nip rollers (8) to be set.

It is advantageous to use high-speed, predominantly adiabatic ones Use extrusion systems whose relatively low weight makes the installation a BüMnF and thus the particularly advantageous way of working from top to bottom permitted.

In a preferred case, the extruders have a screw diameter of approx. 35 - 60 mm and a screw length of 11 D. The screw speed is the same as the diameter and the length of the snail are variable and can be up to 250 ulmin or amount more.

In general, the extruders can both with the same as even to be charged with different material, it is also the application of only one or more than two extruders possible.

After leaving the plastic tube (4) from the blow head (3) and carbon of this hose by blowing it with cooling air is this hose through a flattening device (7) received and fed to the first pair of squeeze rollers (8). When the hose runs into the first pair of squeezing rollers, this hose has a temperature which is just below the welding temperature of the material.

Between the pair of nip rollers (8), which with the speed V is driven and continuously adjustable, and the pair of nip rollers (12), which is also continuously variable driven at speed V, where 2 V can be set equal to V and above, there is a 2 ~ 1 set of rollers (9).

This set of forging rollers mounted in parallel and one behind the other (9) is mounted in the support frame (lOa; lOb) so that the rollers for the purpose of insertion When the film is laid flat and is still warm, it can be opened and closed again can.

The assembly of the forging rollers is made so that each the even-numbered from the odd-numbered rollers with the help of the support frame (lot) resp. (lOb) can be moved apart or together.

The carrier frame (lOa; lOb) are waederum in the present case by hydraulic cylinders (lla; lib> moved, but these can also be done by hand by means of To move spindles, pneumatic cylinders or similar.

In general, the forging rolls (9) are heated by liquid Thermostatized to achieve more precise stretching temperatures, but the thermostatization can be used can be omitted if the cooling of the film is only carried out to the extent that the film temperature reached is identical to the stretching temperature or slightly underneath.

At film temperatures it is slightly below the stretching temperature the desired stretching temperature in the film is surprisingly self-evident the frictional heat generated when the film is stretched.

In the simplest case, the rear rollers (9) are free running and come approximately in a number of 3 - 6 to use.

With increasing working speeds, the number of forging rollers must can be increased to 6 - 12 and above.

In the special case, individual rollers, especially in the second Half of the stretching section, driven and / or for the purpose of temperature control or cooling the foils are thermostated or cooled with liquid media.

An alternating drive for the forging rollers (9) is also a component, if the course of the longitudinal stretching, temperature control and cooling according to one specified program should run.

In such a case, the drives of these forging rollers are only open one side de support frame laid so that only cie idle rollers for the purpose be moved away from the foil guide.

The diameter of the forging rolls is; known to be significant. To the The production of Rascl.elfolien for textile processing is appropriate to the width L of the forging roll, a roll diameter of eta j = 0.04 L to 0.10 L is advantageous.

After leaving the last reci: roller, the film tube is through the pair of nip rollers (12) received and passed on to the deflection rollers (14).

The nip roller pairs (E) and (12) grain even with a given constant Speed ratio V: V increased simultaneously in their 1 2 speeds will.

Between the pair of squeeze rollers (12) and the deflection rollers (14) is the hose is trimmed with the help of a cutting device, divided and also over Deflection rollers fed to the two opposite winders (15a; 15b) so that two webs of one stretched monoaxially in the longitudinal direction in one operation Foil produced and wound into perfectly flat foil rolls without beads can. (16a; 16b) However, it is also possible to use only one winding point and / or wind up the untrimmed hose.

In a special case it is possible to use the hose (4) at a Temperature to reduce the welding of the hose when it enters the Squeeze roller pair (8) causes. Such a hose can also -; t the one proposed Device stretched and processed on each of the two winders (16a; 16b).

EXAMPLE 1 A hose was made from low-density polyethylene 0.959 produced, a material having a melting index according to DIN 53735 of MFI / 190/5 - 1.2 and with a breio The plastic tube bladder was formed at about 210 C on a conventional blow molding machine, cooled, trimmed, separated and wound, each ine flat film with a thickness of about 170 my received chalk.

Following its production, the film was in a second and separate operation by means of a temperature-controlled roller section at an elevated temperature stretched monoaxially and wound up again.

L: e # stretching temperature of the stretching rollers was tisiertem by means of thermostao Oil adjusted to about 128 C, the oil used had the same temperature of 140 C, the set stretching ratio was 750%, so that a final thickness of stretched Fo.F ^ nbahn of about 20 my was obtained.

The film web produced in this way had a trtlbes appearance With a parchment-like handle and already tends to be exposed to manual mechanical exposure in transverse direction for longitudinal splicing.

In a further processing step, this "textile" film was made presented to a so-called Raschel machine, in approx.

2 mm wide Raschel ribbons cut and made into packaging bags or Wrapping nets rustled.

Already when the film was cut into "rustling" tapes Difficulties arise because the film tends to fray when it is cut. This tendency zum Z # rfibres increased during the further: # and actual processing the Raschel machine, which is why the processing process is occasional interrupted It had to be used to acidify and remove the fibers as the guiding elements.

Occasional thread breaks as a result of fiber formation also occurred. the The sacks and nets produced were finally ready after a short one-time use unusable due to fraying.

Example 2 Experiment 1 was repeated, but the suggested one came Device for use, so that the film bubble created with her Was cooled away and in the shortest possible time to stretching temperature and stretched longitudinally. The dwell time; of the hose between the pair of squeeze rollers (8) and the inlet in the stretching section (9) was 4.5 sec., rope temperature of the film -128 C.

The film produced in this way was largely transparent, had one soft grip, could be stretched manually in the transverse direction without splicing and showed also during their further processing during cutting and on the Raschel machine and other textile machines no difficulties.

Sacks made from this film were after eight uses still okay and showed hardly any splice damage #.

Example 3 Experiment 2 was repeated, except that by adjusting different extrusion speeds the residence time of the in approximately adjusted to the stretching temperature hose between the pair of squeezing rollers (8) and the stretching distance (9) could be varied as desired between 2.0 and approx. 15 sec.

To determine the cross splice between the different They sand dwell times after their monoaxial stretching subjected to various tests and practical exams.

The following table shows the splice characteristics n of the various Foils depending on their different dwell times based on a laboratory test and based on a practical test. A "SpleiR-PrUfgeSt" from the FWH came during the laboratory test for use, where the force was measured that was necessary to unite: film to be spliced open using a metal cone. The one for splicing the various The maximum value measured for films is set equal to 100 S in the table below.

The practical test represents the result of the processing on a Raschel machine year.

Dwell time of the hose between (8) and (9) in sec. 2 3.5 5 8.5 9 15 Maximum necessary splicing force 2 ~ n% 100 go 95 89 93 51 Difficulties occur the rustling due to splicing or fibers does not occur. no no no little distinct Experiment 4 In continuation of experiments 2 and 3 were further #research carried out.

Experiment 4a: Production of a Raschel foil material; Low pressure polyethylene according to test 2 extruder: 11 D, 60 mm extrusion temperature of the hose: 230 C hose temperature when entering the pair of squeeze rollers (8): o 120 C distance Squeegee roller pair (8) to the 1st forging roller (9): 1 D squeegee roller pair (8) temperature Speed driven

O with (c) 5 m / with V 1 o 1st forging roll 125 C 5 m / min free running 2. n n 5 n n 3. n II 7 "" 4. n n 19 n 5. n n 38 "6. n n 40 o 7. (tempering roller) 120 C 41 m / min driven 8. n n 110 9. n n 39 "" 10. n n 38 n 11. n "3 37" 12. "n 36 tr º 13. (cooling roller) 50 c 35 m / mLn driven 14." "35" n 15. "" 35 35 "16." "35" "pair of squeeze rollers (12) 35 m / min driven by V 2 the about 1: 7 stretched film is after leaving the last cooling roller of the pair of squeezing rollers (12) picked up, trimmed, deflected and on the two opposite winders wound up. A Raschel sheet with excellent property n is obtained.

4b. Production of a split film Experiment 4a is repeated, however Polypropylene is used as raw material, the production and stretching data being dem Raw material to be adjusted. The speed of the pair of squeeze rollers is used as the stretching ratio (8) with V and the pair of squeeze rollers (12) with V = 10 times 1 2 V. Of the Distance D of the 1st pair of squeezing rollers (8) to the 1st forging roller (9) is about 5 D the squeegee rollers (8) set.

The film obtained is fed to a fibrillation device and shows good fibrillation properties.

When the experiment is repeated, Lib m t 2 extrusion lines under processing For polypropylene with different melt indexes, a film is included in the calculation Preserved fibrillation properties.

Also the use of polyamide or polyester instead of a polyolefin component results in an increase in the splicing tendency of the stretched composite to fine-titrate Split fibers with the help of a downstream fibrillation.

Claims (17)

Claims 1. Process for the continuous H position of in the longitudinal direction monoaxially stretched films in one heat, characterized by the following process steps: a) Formation of a polymer tube with the aid of an extruder and tube nozzle b) Immediate Cooling of the tubular bladder after its formation to temperatures slightly below the welding temperature of the polymer plastic and laying the hose flat c) Immediate pick-up and squeezing of the hose by a pair of squeezing rollers d) Immediate introduction and longitudinal stretching of the hose in one system cascaded, rotating at different speeds Stretching rollers e) Pulling off and picking up the stretched and cooled film tube by a second pair of squeeze rollers driven at increased speed f) takeover of the hose by F: spreading, spreader and / or guide rollers as well if necessary, separation of the film web by trimming it G) Winding up the hose or @. of the separated film webs by winding devices . Method according to claim 1, characterized in that preferably textile films, Woven foils, Raschel foils, split foils, carrier foils for adhesives etc. are produced will 3. The method according to Anso # uch 1, characterized in that crystalline polymer processed such as Polypropylene, low pressure polyethylene, and others, e.g., low pressure polyethylene o with melt indexes MFI / 190/5 of about 0.5 to 5 according to DIN u3755, preferably from approx. 0.5 to 2 4. The method according to claim la, characterized in that two or several extruders are used to produce multiple films, preferably high-speed, adiabatic systems rotating around the hose axis 5. The method according to An # o uch lb, characterized in that for the fastest possible Cooling of the tube bladder Intensive cooling is applied, for example to working temperature set internal and / or external calibration devices and / or additionally temperature-controlled baffles of flattening devices 6. Procedure according to claim lb, characterized uaß the tube bladder in the area of the Crystallite melting points of the polymers is cooled, preferably slightly below, but so far that the welding temperature of the polymer is not reached 7. Procedure according to claim 1d, characterized in that the dwell time of the film tube between the first steplessly re, baren and driven pair of squeeze rollers and the entry into the roller stretching section less than 10 -15 sec., preferably less than 6 - 9 seconds 8. The method according to claim 14, characterized in that the free path of the hose between the 1st pair of squeeze rollers and the inlet in the roller stretching section is about 1 to 2 D of the nip rollers, preferably but less than 1 D 9. The method according to claim ld, characterized in that the forging rolls at different speeds by means of ur # / or are driven by the film to be stretched 10. The method according to claim Id, characterized in that the diameter D d'r stretching rollers are about 0.04 to 0.1 their length L. 11. The method according to claim ld, characterized characterized in that the forging rollers in terms of their temperature program and in terms of of their drives: are set so that the films are stretched and tempered one after the other and can be cooled according to example 4 12. The method according to claim ld-lg, characterized geken @ that the stretched film after receiving and leaving the 2. Pinch roller pair edged, taken up by guide rollers etc., divided and each wound as an independent film web on a 0 # opposite winder ld 13. The method according to one or more of the preceding claims, characterized in that that the axis of symmetry of the entire system compact, vertical or horizontal, preferably however, it is vertically attached, with the formation of the film from top to bottom takes place and without any significant change in direction by deviating and redirecting the foil 14. The method according to one of the preceding claims, characterized in that that a multiple hose by using more extruders and more in their more chemical. id / o 1er rheological structure of different materials: ur achievement of foil. is produced with special properties 15. Device For the preferred implementation of the method according to claims 1 to 14, thereby characterized in that the device consists of the following sub-devices in a compact design consists of a) extrusion system, consisting of extruder (1) and hose nozzle (3) for Formation of a polymer tube (4) b) cooling device immediately afterwards to the hose nozzle (3) for immediate and intensive cooling of the polymer hose (il) immediately after its formation c) driven and steplessly adjustable pair of squeeze rollers (8) for immediately picking up and squeezing off the hose (4) with directly subsequent d) longitudinal stretching section (9), consisting of a system one behind the other switched rollers rotating at different speeds to the immediate Introduction and stretching of the tube e) further at increased speed driven and steplessly adjustable pair of squeeze rollers (12> for peeling and picking up the stretched and cooled film tube f) guiding, holding and / or guide rollers (14) for taking over and guiding the hose, and if necessary Cutting or trimming device (13) g) winding device (16) for Winding up of the film tube or the separate film webs 16. Device according to claim 15, characterized for the preferred production of textile films, Woven foils, Raschel foils, split foils, carrier foils for adhesive tapes, etc. 17. The device according to claim 16, characterized for processing of crystalline polymers such as. B. polypropylene, low-pressure poly pthylene and others, e.g. B. Niederdrucko polyethylene with melt indexes Mm1 / 190/5 of about 0.5 to 5 according to DIN 53735, preferably from about 0.5 to 2 18. Device according to Claim 15a, characterized in that two (la, lb) or more extruders have multiple film tubes form, preferably high-speed adiabatically working and around the tube axis rotating extrusion systems 19. Device according to claim 15b, characterized in that that for immediate and intensive cooling of the tubular bladder (4) immediately after their creation with the help of preferably thermostated liquids cooling mandrels, Calibration cylinders or calibration jackets and / or guide plates are provided 20th Device according to Claim 15b, characterized in that mixtures are used for cooling made of glycerine / water, glycol / water, polyethylene glycol / water and similar systems 21. Device according to claim 15d, characterized in that the distance between the first pair of squeezing rollers (8) and the first forging roller of the stretching system (9) is arbitrarily adjustable 222 device according to claim 15d, characterized in that the first pair of squeezing rollers (8) and the stretching section (9) are attached so that the distance between the first pair of squeeze rollers (8) and the first roller of the stretching section (9) to about 1 to 2 D of the nip rollers is or can be shortened, preferably to less than 1 D 23. Device according to claim 15d, characterized in that the forging rollers (9) run freely 24. The device according to claim 15d, characterized in that the diameter D of the stretching rollers (9) of the stretching device are about 0.04 to 0.1 of their length L. 25. The device according to claim 15d, characterized in that that the forging rollers (9) according to the following sequence and according to the example 4 running freely as forging rollers and then driven as tempering and chill rolls 26. Device according to claim 15d to 15g, characterized in that that the stretching section (9), the second pair of squeeze rollers (12), a trimming device (13), guide and deflection rollers (14) follow, as well as two opposite one another Winder for taking up and winding the separated film webs 27. Device after one or more of the preceding claims, characterized in that all Partial devices are in the axis of symmetry of the overall system, compact and in are arranged preferably vertical operation, with the film from top to bottom formed below and without any significant change in direction due to deviation or; Redirection is stretched and guided. L e r s e i t e