DE1779375C

DE1779375C - Device for stretching a sheet of thermoplastic material

Info

Publication number: DE1779375C
Authority: DE
Inventors: Siegfried DipL-Chem. Dr.; Seifried Walter Dipl.-Chem. Dr.; Gebier Horst Dipl.-Chem. Dr.: 6202 Wiesbaden-Biebrich Janocha
Original assignee: Kalle Ag, 6202 Wiesbaden-Biebrich
Publication date: 1972-11-30

Description

einfachsten Ausführung im wesentlichen aus einem Streckwalzenpaar 2, 3, einer Heizvorrichtung 5 und einem kraftschlüssigen Abzugswalzenpaar G. Eine Folienbahn 1 läuft über die bcheizbarc Walze 2 in einen Sireckspalt 4, der durch die getrennt angctricbencn Walzen 2 und 3 gebildet wird. Die Walze 3 kam, gekühlt werden. Der Walzcnabstand 4 ist in einem Bereich von völligem Kontakt bis zu wenigen Zentimetern verstellbar. Er ist vorzugsweise auf einen Abstand von unter 1 cm eingestellt. Die Beheizung der Folienbahn 1 während der zweiten Streckstufc in einem aus den Walzcnpaaren 2, 3 und 6 gebildeten weiten Spalt 7 kann durch Kontaktwärme, Strahlung oder Heißluft geschehen. Bevorzugt wird ein Heißluftkanal verwendet. Der Abstand der Streckwalzenpaare 2, 3 und 6 muß mindestens in der Größenordnung der Folienbreite liegen, er kann jedoch auch mehrere Meter betragen.The simplest design essentially consists of a pair of drawing rollers 2, 3, a heating device 5 and a non-positive pair of take-off rollers G. A film web 1 runs over the malleable roller 2 into a corner gap 4, which is formed by the separately angular rollers 2 and 3. The roller 3 came to be cooled. The roller spacing 4 can be adjusted in a range from complete contact to a few centimeters. It is preferably set to a distance of less than 1 cm. The heating of the film web 1 during the second stretching step in a wide gap 7 formed from the pairs of rollers 2, 3 and 6 can be done by contact heat, radiation or hot air. A hot air duct is preferably used. The distance between the pairs of drawing rollers 2, 3 and 6 must be at least in the order of magnitude of the width of the film, but it can also be several meters.

Der Einlauf einer Folienbahn 8 gemäß A b b. 2 in einen Streckspalt 12, der durch eine Heizwalze 11 und ein Walzentrio 13 gebildet wird, erfolgt über ein Walzentrio 9 und eine Umlenkwalze 10. Das Walzentrio 13 hat gemäß der gewünschten Streckung eine entsprechend höhere Geschwindigkeit als die Heizwalze 11. Zwischen dem Walzentrio 13 und einem weiteren Walzentrio 16 erfolgt unter Beheizung mit einem Heizofen 15 die zweite Streckung in einem weiten Streckspalt 17.The inlet of a film web 8 according to A b b. 2 in a stretching gap 12, which is formed by a heating roller 11 and a roller center 13 is formed, takes place via a roller center 9 and a deflection roller 10. The Walzentrio 13 has a correspondingly higher speed than that according to the desired stretching Heating roller 11. Between the roller center 13 and a further roller center 16 takes place with heating the second stretching in a wide stretching gap 17 with a heating furnace 15.

Wenn Folicnbändchen hergestellt werden sollen, wird nach dem Walzcntrio 13 die Aufteilung der Folienbahn 8 mit einer Schneidevorrichtung 14 vorgenommen. If foil tapes are to be produced, after the rolling trio 13 the division of the Film web 8 made with a cutting device 14.

An Stelle der Hcizwalze 11 in Abb. 2 kann auch in bekannter Weise ein Hcizwalzensystcm 18 in der in Abb. 3 dargestellten Form gewählt werden. In dieser Anordnung findet die erste Streckung in einem Spalt 20 zwischen Walzen 19,21 und die zweite Streckung zwischen der Walze 21 und einem Abzugswalzensystem 23 in einem Strcckspalt 24 unter Beheizung mittels einer Heizvorrichtung 22 statt. Bei dieser Anordnung erfolgt beispielsweise die Aufteilung der Folienbahn in Bändchen nach der Gesamtstreckung mit einer Schneidevorrichtung 25. Eine Aufteilung der Folienbahn an dieser Stelle ist jedoch nur dann zweckmäßig, wenn das Längsstreckverhältnis nicht sehr groß ist und die monoaxial gestreckte Folienbahn sich noch einwandfrei schneiden läßt.Instead of the heating roller 11 in FIG. 2, a heating roller system 18 can also be used in a known manner can be selected in the form shown in Fig. 3. In this arrangement the first stretch takes place in one Gap 20 between rollers 19, 21 and the second stretching between roller 21 and a take-off roller system 23 takes place in a stretching gap 24 with heating by means of a heating device 22. at In this arrangement, for example, the film web is divided into ribbons after the overall stretching with a cutting device 25. A division of the film web at this point is, however only expedient if the longitudinal stretching ratio is not very large and the monoaxially stretched one Foil web can still be cut properly.

Eine Vorrichtung, bei der die Streckung sowohl im engen Spalt als auch im weiten Spalt mehrstufig sowohl im engen Spalt als auch im weiten Spalt mehrstufig durchgeführt werden kann, ist in A b b. 4 dargestellt. Die erste Streckung wird in an sich bekannter Weise'in Spalten 26, 27 und 28 durchgeführt, während die Folgestreckungen unter Beheizung mit Heizöfen 29 und 31 mit Hilfe von Strecktrios 30 und 32 auf langen Wegen 33 und 34 durchgeführt werden.A device in which the stretching in a narrow gap as well as in a wide gap takes place in several stages can be carried out in multiple stages both in the narrow gap and in the wide gap, is in A b b. 4th shown. The first stretching is carried out in a manner known per se in columns 26, 27 and 28, while the subsequent stretching under heating with heating ovens 29 and 31 with the help of stretching trios 30 and 32 can be carried out on long paths 33 and 34.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

1 21 2

Ratio of the decrease in width and thickness of a film

Claim: and consequently their achievable properties

given longitudinal stretching ratio set arbitrarily

Device for stretching a film web can be.

made of thermoplastic material with several 5 The task is described in the introduction solved by two rollers or roller arrangement device in that, in passages formed stretch gaps, seen the direction of the film web, at least one The roll axes widen perpendicularly to the straight-through direction of the narrow stretching gap in front of one or more extend device, thereby marked stretching gaps is arranged.

net that, in the direction of travel of the film web io under roller arrangements are in this context

seen, at least one narrow stretch gap in front of menhang, for example, pairs of squeeze rollers or

to understand roller systems similar to one or more wide stretching gaps,

is arranged. It has now been found that the combination

known stretching arrangements to a two- or

is a multi-step process in which the stretching is in close proximity

Gap takes place before stretching in the wide gap, in

Depending on the distribution of the total stretching ratio among the stretching angles, a surprising result great variation in the control of the

The invention relates to a device for reducing the width and thickness of the Foliv. the Stretching a sheet of film made from a thermoplastic device is therefore not suitable for producing plastic with more than one set by two rollers each, not or strongly spliceable or roller arrangements formed stretch strips, foils, but also for the production of foils whereby the roller axes are perpendicular to the diameter with the whole; certain splicing associated with extend the running direction of the film web. 25 great strength.

Devices for the production of longitudinally stretched thermoplastic films are known with the devices according to the invention. The monoaxial stretching of a film web in a multi-stage stretching device is also described, in which the known stretching systems can be carried out in ways that allow the widths of the stretching gaps to be adjusted beyond the possibilities of the known stretching systems. In the devices mentioned, the properties of the film web can split, ie can be largely controlled on one or more stretching paths, by the ratio of the stretching over a short stretching either in one or more roller paths and over a long stretching path. One, with the use of several roller nips, this brings about stretching in the narrow stretching gap, each having the same width. The type of pulled on the end film, an increased decrease in thickness, dimensional change of the film during the stretching process. A reduced pulp contraction process is very different. While with yourself. This results in a low tendency to spit, stretching over a short stretching path of the material flow and high elongation at break with good tear strength. A predominantly from the film thickness occurs when the stretching ratio is shifted in favor of stretching on the long stretching path, both a thickness re-stretching on the long stretching path changes and a decrease in width in a comparable way to the film properties in the direction of a higher splice percentage order of magnitude. Corresponding to the tendency and low elongation at break with consistently different dimensional changes in the film with high or increased tear strength,
The device according to the invention is also different from the various stretching processes, given the longitudinal stretching ratio specified in the output rate for film webs, the orientation of the final thickness and the given high take-off speed effects and thus the properties of the film. Known devices also superior. Devices with a narrow gap do not provide any or only a little because of the small width contraction and the only minimally splittable foils, since as a result of the strong decrease in thickness in the first stretching stage in the small width contraction there is no maximum narrow gap, the output is higher than with orientation effects. The big stretching 50 single-stage stretching process is well on its way. Counter-speeds in the narrow gap also allow for the one-step stretching in the narrow gap, there are also necessary high longitudinal stretching ratios in the case of splitting the stretching in the described connection with economically interesting take-off manner no limitations in the throughput speeds. speed and in the maximum longitudinal stretch, however, devices with wide gap 55 provide ratios. There can be haul-off speeds compared to those with a narrow high orientation up to the handling limit of about 200 m / min. Stretching ratios and take-off and beyond can be achieved. The inventive speeds are limited by the arrangement not according to the device is particularly well suited for. In contrast, the final width of the film is greatly reduced as a result of stretching film webs made of a polyolefin, which is subject to greater rider contraction. It can be seen from an olefin copolymer or a polymer that the mixture for use with a proportion of polyolefin,
The device according to the invention is explained in more detail on the basis of hand shafts such as final dimensions, strength, elongation, the drawing.
Splicing tendencies are related to each other A b b. 1 shows schematically the device in general and, given the raw material, a function of the respective general form in side view and top view;
because the device is used. A b b. 2, 3 and 4 show further embodiments

The invention has for its object to form a side view.

To develop stretching device with which the device consists according to A b b. 1 in the