EP2470441B1

EP2470441B1 - Use of a biaxially oriented film roll made of polypropylene for cigarette packages, and cigarette carton

Info

Publication number: EP2470441B1
Application number: EP10752721.0A
Authority: EP
Inventors: Angela Speith-Herfurth; Patrick Stuppi; Leo Wintrich; Jörg STEINBRECHER; Markus Henne
Original assignee: Treofan Germany GmbH and Co KG
Current assignee: Treofan Germany GmbH and Co KG
Priority date: 2009-08-28
Filing date: 2010-08-26
Publication date: 2018-10-10
Anticipated expiration: 2030-08-26
Also published as: WO2011023385A1; UA115860C2; MX2012002474A; CN102498047B; AU2010288875A1; PL2470441T3; CN102498047A; EP2470441A1; AU2010288875B2; BR112012004390A2; EA023195B1; ZA201201384B; JP2013503080A; CA2771912A1; KR20120059519A; EA201270329A1; DE202010018143U1; US20120152773A1

Description

The present invention relates to a use of a biaxially oriented film roll according to claim 1 and a cigarette rod according to claim 7.
The success of biaxially oriented plastic films, particularly thermoplastic polymer films, and especially biaxially oriented polypropylene films, is essentially due to their excellent mechanical strength properties in conjunction with comparatively low weight, good barrier properties and good weldability. The polyolefin film protects the packaged goods against rapid drying or loss of flavor with very low material usage.
The desire of the consumer for a hygienic, visually appealing, tightly closed and resistant packaging is opposed to the desire for an easy and controllable opening. The latter is criticized by consumers in the packaging of polyolefin films and regarded as a disadvantage compared to paper packaging.
Uniaxially oriented films show a low tear strength in the direction of orientation and can be easily controlled in this direction and tear further. However, uniaxially oriented films are not usable in many fields, among other things due to insufficient transverse mechanical strengths. The biaxial orientation, on the one hand, produces the desirable high strengths (moduli) in both dimensions; on the other hand, but also the preferred directions are equalized. This has the consequence that for opening a film package (eg biscuit bag) first a high force must be overcome in order to tear the film. However, once the film has been injured or scratched, a crack will be planted even when using very low tensile forces uncontrollably continued. These inadequate service properties due to an excessively high tear strength in combination with a very low tear strength reduce the acceptance of film packaging in the end consumer market, despite the advantages mentioned at the outset.
In the prior art it has been proposed to provide the film with a predetermined breaking point. When opening, the film breaks in this predetermined breaking point. Nevertheless, the crack often propagates very uncontrolled, since these solutions facilitate tearing but do not really help with controlled tearing.
Another known possible solution is the mechanical installation of a predetermined breaking point in the form of a perforation or notches along an imaginary opening line. Often, however, such a perforation does not ensure a controlled tearing. When opening the crack follows only initially the perforation line and then continues but arbitrarily divergent in the material.
This uncontrolled tear propagation behavior is particularly problematic in biaxially oriented polypropylene films, since the tear propagation resistance is particularly weak in this material. This problem is particularly troublesome for packages with general cargo, which is not loose, but packaged orderly, such as cigarette rods, Weetabix, crispbread, biscuit rolls and the like. These types of packaging are particularly designed to ensure that the consumer initially only picks individual pieces and wants to store the remainder of the package in order to remove more units at a later date. For this application, the uncontrolled tear propagation of the film packaging is particularly annoying for the consumer.
The WO 98/2312 describes packages that are pre-cut by a laser beam. These packages have a multilayer structure. In particular, a metallic intermediate layer is provided which is intended to prevent the laser beam from cutting through the film. This packaging is lavish and expensive due to the lamination with a metal layer. About the exact configuration of the packaging is disclosed in the description nothing. The WO 98/2312 describes packages that are pre-cut by a laser beam. These packages have a multilayer structure. In particular, a metallic intermediate layer is provided which is intended to prevent the laser beam from cutting through the film. This packaging is lavish and expensive due to the lamination with a metal layer. About the exact configuration of the packaging is disclosed in the description nothing. The WO 98/2312 describes packages that are pre-cut by a laser beam. These packages have a multilayer structure. In particular, a metallic intermediate layer is provided which is intended to prevent the laser beam from cutting through the film. This packaging is lavish and expensive due to the lamination with a metal layer. About the exact configuration of the packaging is disclosed in the description nothing.
In addition, the perforated film must have sufficient mechanical stability so that the perforated film can be used to package the piece goods. There are described in the prior art method in which the perforation is integrated as a processing step in the packing process. This solution avoids any mechanical stresses on the perforated film, e.g. when winding and unwinding. However, the integration of the perforation is not possible in all packaging processes. Firstly, the spatial conditions in existing systems are often designed so that there is simply no room to grow such a device. Furthermore, the packaging processes in the cigarette industry are running at very high speeds, which may be too fast for the perforation. Therefore, it is not always possible to incorporate a device for perforating the foil into a device for bar wrapping cigarette packets. A sufficient mechanical stability of the film is contrary to the same desire for an easy-open packaging.
The EP1764313 discloses the use of a biaxially oriented polypropylene film as a packaging material for repackaging packed articles. The packaging material has two thin lines which are arranged parallel and offset from one another. However, the thin spots are shorter than the distances between the thin spots. The EP1764313 discloses the use of a biaxially oriented polypropylene film as a packaging material for repackaging packed articles. The packaging material has two thin lines which are arranged parallel and offset from one another. However, the thin spots are shorter than the distances between the thin spots. The EP1764313 discloses the use of a biaxially oriented polypropylene film as a packaging material for repackaging packed articles. The packaging material has two thin lines which are arranged parallel and offset from one another. However, the thin spots are shorter than the distances between the thin spots.
describes an axially oriented shrink film made of polypropylene with at least two thin-point lines which run parallel to one another. The shrink film is used as a sleeve for cylindrical vessels and for this purpose it is shrunk onto the vessel. The parallel thin lines form a kind of tear-off tape, via which the sleeve can be torn open and separated from the vessel. JP2006-276515 describes an axially oriented shrink film Polypropylene with at least two thin-line lines, which run parallel to each other. The shrink film is used as a sleeve for cylindrical vessels and shrunk onto the vessel for this purpose. The parallel thin lines form a kind of tear tape over which the sleeve can be torn open and separated from the vessel.
describes a method of wrapping an article using a packaging film having at least one tear line. This describes in detail how the film is cut and processed to produce a sealed package with a specially designed strip. The package can then be opened simply by pulling the free end of the strip to initiate tearing along the tear line. WO03072455 describes a method of wrapping an article using a wrapping film having at least one tear line. It will be described in detail how the film is cut and processed to produce a sealed package with a specially designed strip. The package can then be opened simply by pulling the free end of the strip to initiate tearing along the tear line.
discloses a cigarette rod and the use of a shrinkable film made of polypropylene for the packaging of cuboid cigarette packs. DE102006013280 including a cigarette rod and the use of a polypropylene shrinkable film for packaging cuboid cigarette packets.
The object of the present invention was to provide an improved package for ordered cargo available.
The object underlying the invention is achieved by the use of a biaxially oriented film roll of polypropylene according to claim 1.

Figure 1 shows an embodiment of the film (2) with circular thin places (1) with a length (diameter) B. The length of the distances between the thin places corresponds to the length A. Both parallel thin lines are arranged at a distance of C from one another. In the embodiment according to Fig. 1 the distances A are just as long as the length of the thin points B. The thin point lines are offset from one another in such a way that the center of the respective thin point is aligned with the center of the opposite distance.
Figure 2 shows a film with circular thin spots whose length B is greater than the distances A.
Figure 3 shows thin spots with a rectangular geometry, where B> A here too.
Fig. 4 shows a film not according to the invention with diamond-shaped perforations, such as those produced, for example, by rotating knives.
Fig. 5 shows a film with elliptical thin spots. Here, too, B> A.
Fig. 6 shows a possible geometry of a needle perforation not according to the invention, in which propeller-like perforations arise.
Fig. 7 shows a film web which has a plurality of thin-digit double lines in the longitudinal direction.
Fig. 8 shows a piece goods packaging (3), which is opened by breaking off along the thin-point double line (4).

The object is further achieved by a cigarette rod according to claim 7.

FIG. 1 shows an embodiment of the film (2) with circular thin points (1) with a length (diameter) B. The length of the distances between the thin locations corresponds to the length A. Both parallel thin lines are arranged at a distance from each other C. In the embodiment according to Fig. 1 the distances A are the same length as the length of the thin spots B. The thin line are arranged offset from one another so that the center of the respective thin spot is aligned with the center of the opposite distance.
FIG. 2 shows a film with circular thin points whose length B is greater than the distances A.
FIG. 3 shows thin areas with a rectangular geometry, where again B> A.
Fig. 4 shows a non-inventive film with diamond-shaped perforations, such as those produced by rotating knives.
Fig. 5 shows a film with elliptical thin areas. Again, B> A.
Fig. 6 shows a possible geometry of a non-inventive needle perforation in which arise propeller-like perforations.
Fig. 7 shows a film web having a plurality of thin-point double lines in the longitudinal direction.
Fig. 8 shows a package (3), which is opened by breaking along the thin line double line (4).

All of these embodiments according to the FIGS. 1 to 8 is common that the distances A between the thin bodies are equal to or smaller than the length B of the thin body itself.
The two parallel, staggered thin-point lines form a predetermined breaking point in the film, in which a crack propagates very controlled after tearing. The tear continues to run after tearing along one of the thin-line or between the two parallel thin-line lines controlled. The foil packaging is opened only as far as desired.
The packaging according to the invention is particularly suitable for ordered or stacked piece goods, e.g. Cigarette packet, suitable. It is possible for the consumer to tear the film along a predetermined predetermined breaking point in such a way that individual pieces can be removed without further units falling out uncontrollably in the case of piece goods. The individual segments between the parallel thin-line lines are adapted according to the size of the unit to be removed. This can be used to control whether one or more units can be conveniently removed by opening.
The thin-line lines can be applied to the film web in a suitable pattern. Preferably, the lines are straight. However, it is also possible to apply the line with any geometric shape, so that the predetermined breaking point later the shape and dimensions of packaged piece goods corresponds.
For the purposes of the present invention, thin locations are understood as meaning thin areas in which no continuous hole is produced in the film, but the film only becomes thinner at the corresponding points due to removal of material, for example by a laser beam which only penetrates to a predetermined depth. In these embodiments, 10 to 80% of the original film thickness, preferably 20 to 60% of the original film thickness in the region of the thin location remain. In this way, a closed package is obtained, which continues to meet all hygienic requirements and their barrier properties are not impaired.
Along the thin-point line thin sections (thin sections B) are followed by undamaged sections of film whose length A is determined by the distance of the thin places. Distances are for the purposes of the present invention thus the areas of undamaged film, ranging from the end of a thin spot to the beginning of the subsequent thin spot in the same thin line.
The geometric shape of the thin site may vary and depends on the thin point method. For thin-site lines from non-continuous thin sites, laser or ultrasound is preferred. Needle perforations create circular or ellipsoidal or propeller-like shapes that result from the needle and foil contacting each other at the perforation and moving relative to each other. Knives produce more rectangular or diamond-shaped thin spots. Laser and ultrasound methods allow different geometric shapes. Except for circular thin spots, all thin spots have a greater extension in one of the two fundamental directions (longitudinal direction) aligned along the thin line.
The thinnings have in the longitudinal direction generally a length B of 0.1 to 8 mm, preferably 0.3 to 6 mm, in particular 0.5 to 3 mm. The extent of the thin point transversely to this longitudinal direction is correspondingly smaller and is generally 5 to 80%, preferably 10 to 50% of its extension in the longitudinal direction. This does not apply to circular thin areas. Circular and approximately circular thin bodies have a diameter of 0.1-6 mm, preferably 0.3 to 5 mm, in which case the diameter corresponds to the length of the thin body B.
For a particularly low tearing force, in particular thin sites with a length of> 1 to 6 mm are preferred, in particular also lengths of 1.5 to 6 mm or 2 to 4 mm are suitable. Surprisingly, the mechanical strengths of the film are not affected even in these comparatively large or long thin areas. These embodiments can be excellent to wind up a film roll and unwind easily on the packing machine again.
The length A of the sections, i. the undamaged film between the thin points is 0.05 to <8mm, preferably 1 to 6mm. For embodiments with long thinnings of, for example, 1.5 to 6 mm, distances of> 4 to 10 mm are preferred. The dimensions of the distances A are selected in relation to the length B of the thin spot so that this length B of the thin sites are at least as large or larger than the distances A. In general, the length or diameter of a thin spot is at least 10% greater than the length of the gaps. In general, the length A of the gaps is 10 to 90% of the length B of the thin spots, preferably 20 to 85%.
The dimensions given for the thin locations and distances apply in the same way also for thin bodies which are circular, elliptical or can be elongated.
Along a line, the dimensions of the distances between the thin spots are generally constant, or vary only slightly within the usual manufacturing accuracy. Likewise, the size of each thin spot along a line does not or only slightly varies (up to 10%). For example, the diameter of the holes or the length of a thin spot is constant. Likewise, the thin points and distances of the two parallel thin-line lines of a predetermined breaking point have approximately the same dimensions.
It is essential to the invention that an intended breaking point is formed from two thin lines running in parallel, which are arranged at a distance C of not more than 10 mm. The distance C of these two lines is preferably 0.5 to 8 mm, in particular 0.8 to 5 mm
The second essential feature of the predetermined breaking point according to the invention is the arrangement of the thin places of the two parallel thin-layer lines to each other. It has been found that staggered placement of the thin spots of the two lines improves the control of crack propagation surprisingly. In this staggered arrangement, a thin spot of the second line does not start at the same height as the opposite thin spot of the first line. As a result, the thin point of the second line at least partially covers the distance of the first thin-line line. In preferred embodiments, especially those in which the thin spots are larger than the spacings, the sections of the one thin line are completely covered by the thin spots of the opposite lines.
In a preferred embodiment, the center of the sections of the first thin line is aligned with the center of the respective opposite thin points of the second thin line, so that a symmetrical Thin-point pattern arises.
Surprisingly, the arrangement of two parallel, staggered thin-line lines significantly improves the control of the crack profile. The invention also makes it possible to break off the packaging at the predetermined breaking point over the edges of the piece goods if the piece goods have a corresponding mechanical stability and the piece goods in the package is arranged so that its edge extends at the level of the double line.
The thin-line lines are generally applied in the machine direction of the film. This can be combined simultaneously with the cutting of the film to narrower film widths and thus be carried out in one operation. Alternatively, this can also be done before or after cutting to the finished film width. In all these variants of the method, the film can for example be guided over rollers with suitable tools, for example, these rollers are equipped with knife blades. When using laser or ultrasound to create the thin sites, corresponding tools are positioned below or above the film web. In these processes, the film is unwound from a roll, the thin spots according to the invention are applied, and the thinned film is subsequently rewound and the roll used at the general cargo packaging facilities, ie unwound and used for wrapping the goods. Surprisingly, the thin areas do not impair the winding behavior of the film or only insignificantly, so that the thin film provided with the usual devices can be wound up and unwound. It has also been found, surprisingly, that the thin areas according to the invention do not impair the mechanical stability of the film in such a way that the film breaks, film tears, thick places or thinnings arise during winding and unwinding.
The roll of thinned film is used to make the package of the present invention. The packaging according to the invention is particularly suitable for ordered or stacked piece goods. It is possible for the consumer to tear the film along a predetermined predetermined breaking point in such a way that individual pieces can be removed without other uncontrolled fall out in the case of general cargo. The individual segments are adapted according to the size of the unit to be removed. This can be used to control whether one or more units can be conveniently removed after opening.
The film used is generally a biaxially oriented film of polypropylene. Depending on the type of packaging, the film can be a translucent to transparent or an opaque film. For the purposes of the present invention, "opaque film" means an opaque film whose light transmittance (ASTM-D 1003-77) is at most 70%, preferably at most 50%. The film can basically be constructed as a single layer or as a multilayer. Also suitable for the packaging according to the invention are laminates, which are preferably constructed from the films described herein.
For transparent embodiments, the formulation of the film and the type of laser can be coordinated so that the laser beam in the field of thinning leaves a white or colored line. Thus, the package later has a recognizable mark and indicates to the consumer where the crack to open the package to allow convenient handling.
Possible thermoplastics for the film are polyolefins of olefinic monomers having 2 to 8 carbon atoms. Propylene polymers, ethylene polymers, butylene polymers, cycloolefin polymers or copolymers of propylene, ethylene, butylene units or cycloolefins are particularly suitable. In general, the layers of the film, or the layer for single-layer embodiments, at least 50 wt .-%, preferably 70 to 99 wt .-%, in particular 90 to 98 wt .-%, of the thermoplastic polymer, each by weight the layer.
As polyolefins, propylene polymers are preferred. These propylene polymers contain 90 to 100 wt .-%, preferably 95 to 100 wt .-%, in particular 98 to 100 wt .-%, of propylene and has a melting point of 120 ° C or higher, preferably 130 to 170 ° C, and im in general, a melt flow index of 0.5 g / 10 min to 15 g / 10 min, preferably 2 g / 10 min to 10 g / 10 min, at 230 ° C and a force of 21.6 N (DIN 53 735). Isotactic propylene homopolymer having an atactic content of 15% by weight and less, copolymers of ethylene and propylene having an ethylene content of 10% by weight or less, copolymers of propylene with C 4 -C 8 olefins having an olefin content of 10% by weight. % or less, terpolymers of propylene, ethylene and butylene having an ethylene content of 10% by weight or less and having a butylene content of 15% by weight or less are preferred propylene polymers for the core layer, with isotactic propylene homopolymer being particularly preferred. The stated percentages by weight relate to the respective polymer.
Furthermore, a mixture of said propylene homo- and / or copolymers and / or terpolymers and other polyolefins, in particular from monomers having 2 to 6 carbon atoms, suitable, wherein the mixture at least 50 wt .-%, in particular at least 75 Wt .-%, containing propylene polymer. Suitable other polyolefins in the polymer blend are polyethylenes, especially HDPE, LDPE, VLDPE and LLDPE, wherein the proportion of these polyolefins each 15 wt .-%, based on the polymer mixture, does not exceed.
If appropriate, a layer, preferably the base layer or an intermediate layer, of the film for opaque embodiments may additionally contain pigments and / or vacuole-initiating particles in customary amounts.
The film of the invention may be single-layered, preferably the film is multi-layered. For this purpose, one or both sides of the intermediate layer and / or cover layers may be applied to the base layer. Accordingly, multi-layered embodiments of the film in addition to the base layer, optionally intermediate layers and outer layers.
These additional cover layers and / or intermediate layers are generally composed of polyolefins. They contain at least 70 wt .-%, preferably 75 to 100 wt .-%, in particular 90 to 98 wt .-%, of a polyolefins. As polyolefins for these additional layers are basically the same polymers as described above for the base layer.
Ethylene and another olefin having 5 to 10 carbon atoms or
Propylene and another olefin having 5 to 10 carbon atoms or a terpolymer of
Ethylene and propylene and butylene or
Ethylene and propylene and another olefin having 5 to 10 carbon atoms or
Mixtures or blends of two or more of the homo-, co- and terpolymers mentioned are suitable. For the cover layers are
Copolymer of
Ethylene and propylene or
Ethylene and butylene or
Propylene and butylene or
Ethylene and another olefin having 5 to 10 carbon atoms or
Propylene and another olefin having 5 to 10 carbon atoms or a terpolymer of
Ethylene and propylene and butylene or
Ethylene and propylene and another olefin having 5 to 10 carbon atoms or
a mixture or blends of two or more of said homo-, co- and terpolymers suitable.
an ethylene content of 2 to 10% by weight, preferably 5 to 8% by weight, or random propylene-butylene-1 copolymers with
a butylene content of 4 to 25% by weight, preferably 10 to 20% by weight, based in each case on the total weight of the copolymer, or
ethylene-propylene-butylene-1 random terpolymers with
an ethylene content of 1 to 10% by weight, preferably 2 to 6% by weight, and a butylene-1 content of 3 to 20% by weight, preferably 8 to 10% by weight, each based on the total weight of the terpolymer, or
a blend of an ethylene-propylene-butylene-1 terpolymer and a propylene-butylene-1 copolymer
with an ethylene content of 0.1 to 7% by weight
and a propylene content of 50 to 90% by weight
and a butylene-1 content of 10 to 40% by weight,
each based on the total weight of the polymer blend,
particularly preferred. Below are
ethylene-propylene random copolymers with
an ethylene content of 2 to 10 wt .-%, preferably 5 to 8 wt .-%, or random propylene-butylene-1 copolymers with
a butylene content of 4 to 25 wt .-%, preferably 10 to 20 wt .-%, each based on the total weight of the copolymer, or
ethylene-propylene-butylene-1-terpolymers with
an ethylene content of 1 to 10 wt .-%, preferably 2 to 6 wt .-%, and a butylene-1 content of 3 to 20 wt .-%, preferably 8 to 10 wt .-%, each based on the total weight of the terpolymer, or
a blend of an ethylene-propylene-butylene-1 terpolymer and a propylene-butylene-1 copolymer
with an ethylene content of 0.1 to 7% by weight
and a propylene content of 50 to 90 wt .-%
and a butylene-1 content of 10 to 40% by weight,
in each case based on the total weight of the polymer blend,
particularly preferred.
The co- or terpolymers described above generally have a melt flow index of from 1.5 to 30 g / 10 min, preferably from 3 to 15 g / 10 min. The melting point is in the range of 120 to 140 ° C. The blend of copolymers and terpolymers described above has a melt flow index of 5 to 9 g / 10 min and a melting point of 120 to 150 ° C. All above-mentioned Schmelzflußindices are measured at 230 ° C and a force of 21.6 N (DIN 53 735). Layers of co- and / or terpolymers preferably form the outer layers of sealable embodiments of the film.
The total thickness of the film can vary within wide limits and depends on the intended use. The preferred embodiments of the film have total thicknesses of 5 to 250 microns, with 10 to 100 .mu.m, in particular 20 to 80 microns, are preferred.
For the purposes of the present invention, the base layer is the layer which makes up more than 50% of the total thickness of the film. Their thickness results from the difference between the total thickness and the thickness of the applied cover and intermediate layer (s) and can therefore vary within wide limits analogously to the total thickness. Cover layers form the outermost layer of the film and are 0.5 to 5 microns, preferably 1 to 3 microns. The intermediate layer is between 1 and 20 microns, preferably 1 to 10 microns.
In order to further improve certain properties of the polypropylene film according to the invention, both the base layer and the intermediate layer (s) and the topcoat (s) may contain additives in an effective amount, preferably hydrocarbon resin and / or antistatics and / or antiblocking agents and / or lubricants and / or or stabilizers and / or neutralizing agents which are compatible with the polymers of the core layer and the top layer (s), with the exception of the generally incompatible antiblocking agents.
The films are produced by the extrusion process known per se. In the context of this process, the melts corresponding to the individual layers of the film are extruded through a flat die. The film thus obtained is stripped to solidify on one or more roll (s) and cooled. The temperature of the take-off roll or rollers is 10 to 90 ° C, preferably 20 to 60 ° C.
Subsequently, the film is stretched biaxially. The biaxial stretching can be carried out simultaneously or sequentially, with the successive biaxial stretching in which stretching is first longitudinal (in the machine direction) and then transverse (perpendicular to the machine direction) is particularly favorable. In the longitudinal direction is preferably 3: 1 to 7: 1 and at a temperature of less than 140 ° C, preferably in the range of 125 to 135 ° C stretched. In the transverse direction is preferably 5: 1 to 12: 1, at a temperature of greater than 140 ° C, preferably at 145 to 160 ° C, stretched. The longitudinal stretching will be carried out expediently with the help of two different speeds corresponding to the desired stretching ratio and the transverse stretching with the aid of a corresponding clip frame. In principle, biaxial stretching can also be carried out simultaneously in the longitudinal transverse direction. These simultaneous stretching methods are known per se in the prior art.
For heat setting (heat treatment), the film is finally held at a temperature of 110 to 150 ° C for about 0.5 to 10 seconds. Optionally, as mentioned above, after biaxial stretching, one or both surfaces of the film may be corona or flame treated by one of the known methods.
Optionally, after production but before perforation, the film may be laminated, coated, melt-coated, painted or laminated by further processing steps to provide the film with further advantageous properties. As laminates, composites of polypropylene films and polyethylene films are particularly preferred. Such composites can be produced by lamination of the individual films. Another technically advantageous variant for the production of PP / PE laminates is the extrusion coating of a suitable polyethylene onto a biaxially oriented polypropylene film. Such extrusion coatings are known per se in the prior art. It has been found that laminates of PP / PE films are advantageous in the treatment by laser beam and are less likely to be perforated by mistake.
The packaging is characterized by a controllable tear behavior. Optionally, the force required to initiate a tear at the foil edge can be reduced by a notch, preferably V-shaped. The packaging is much easier and more controlled to continue. In addition, it also shows all the advantages that conventional film packaging also have, such as high mechanical strength, water and oxygen barrier, good optical properties.
The packaging is particularly advantageous for use with piece goods, especially for stacked units, such as e.g. Biscuits, packets of cigarettes or pressed food moldings.
The foil with the perforation enables a novel packaging solution for cigarette rods. The packets of cigarettes are stacked and wrapped in the film with the perforation according to the invention. These cigarette rods can then be opened at the predetermined breaking point by breaking along the perforation line.
The invention is explained in more detail by the following examples:

example 1

A transparent three-layer ABA film with a symmetrical structure with a total thickness of 20 μm was produced by coextrusion and subsequent stepwise orientation in the longitudinal and transverse directions. The cover layers had a thickness of 0.6 μm in each case.

B-base layer:

Approximately 90% by weight Propylene homopolymer having a melting point of 162 ° C and a melt flow index of 3.4 g / 10min 0.15% by weight N, N-bis-ethoxyalkylamine (antistatic) 0.30% by weight erucamide

A top layers:

about 75% by weight Ethylene-propylene random copolymer having a C2 content of 4.5% by weight about 25% by weight Ethylene-propylene-butylene random terpolymer having an ethylene content of 3% by weight and a butylene content of 7% by weight (remainder of propylene) 0.33% by weight SiO 2 as antiblocking agent with an average particle size of 2 microns 0.90% by weight Polydimethylsiloxane with a viscosity of 30 000 mm2 / s
The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C The production conditions in the individual process steps were: extrusion: Temperatures base layer: 260 ° C outer layers: 240 ° C Temperature of take-off roll: 20 ° C Longitudinal stretching: Temperature: 110 ° C Longitudinal stretching ratio: 5.5 Transverse stretching: Temperature: 160 ° C Transverse stretching ratio: 9 fixation: Temperature: 140 ° C Convergence: 20%
The film was then coated on a surface with a sealable acrylate coating.
The film was then cut to 350mm width into narrow cuts and wound up. These narrow cuts (rolls) were passed in a second step on a needled rollers and provided in the longitudinal direction of the film with perforation lines, which were arranged in parallel at a distance of 6mm. The perforation had a propeller-like shape with a length B of 4 mm. The distances between the individual perforations was 2mm. The thus perforated film was wound up into a roll of perforated film.
The perforated film was then used for a bar wrap with 12 cigarette sachets. The packets were arranged so that the edges of the packets were at the level of the perforation line. The packets could be removed by breaking along the perforation line, without causing uncontrolled crack propagation in the film.

Comparative example

A single-row perforation was applied to the film described in Example 1 with a similar needle roller. The perforations were the same length and spacing as in Example 1. The film was used in the same way for the bar wrap of 12 cigarette sachets. The packaging could not be opened by breaking. When attempting to tear the film along the perforation line, 3 out of 10 attempts led to an uncontrolled tear along the perforation line.

Claims

Use of a biaxially oriented film roll of polypropylene with lines of thin areas for packaging rectangular cigarette packages, characterized in that the film has at least two lines of thin areas running parallel to one another, situated at a distance (C) of 10 mm at most, wherein the thin areas (1) of the two lines are arranged with an offset from one another, wherein there are intervals (2) of undamaged film between the thin areas (1), and the thin areas (1) are longer than or exactly as long as the intervals (2) between the thin areas (1), and the thin areas (1) comprise 10% to 80% of the remaining thickness of the film.
Use of a polypropylene film roll according to claim 1, characterized in that the thin areas (1) are created by abrasion of material using a laser beam or ultrasound.
Use of a polypropylene film roll according to claim 1, characterized in that the thin areas (1) are created by means of a blade and are in the form of diamonds or rectangles.
Use of a polypropylene film roll according to claim 1, characterized in that the thin areas (1) are 0.1-8 mm long.
Use of a polypropylene film roll according to claim 1, characterized in that the length of the intervals (A) between these thin areas (1) amounts to 10% to 95% of the length (B) of the thin areas (1) .
Use of a polypropylene film roll according to claim 1, characterized in that the centers of the sections of the first line of a thin area are flush with the centers of the opposing thin areas in the second line of a thin area.
Cigarette cartons, containing rectangular packs of cigarettes, comprising a biaxially oriented polypropylene film, characterized in that the film has at least two lines of thin areas running parallel to one another, situated at a maximum distance (C) of 10 mm, and wherein the thin areas (1) of the two lines are arranged with an offset from one another, wherein there are intervals (2) of undamaged film between the thin areas (1), and the thin areas (1) are longer than or exactly as long as the intervals (2) between the thin areas (1), wherein the thin areas constitute 10% to 80% of the remaining film thickness, and wherein the cigarette carton is manufactured by using any one of claims 1 to 6.