CN102498047B - With the polypropylene screen opening auxiliary mechanism - Google Patents

Abstract

Introduce a kind of biaxially oriented film (2) be made up of polypropylene with line of perforations.Described film has at least two line of perforations, and described line of perforations distributes parallel with respect to each other .ly, and is in the interval of maximum 10mm.Article two, the perforate (1) of line is arranged with offseting one from another.

Description

Polypropylene membrane with opening aid

technical field

The present invention relates to: a biaxially oriented polypropylene film with apertures; and a package made of biaxially oriented polypropylene film having apertures as opening aids.

Background technique

The success of biaxially oriented plastic films, especially films made of thermoplastic polymers, and especially biaxially oriented polypropylene films, is primarily based on their excellent mechanical strength properties combined with relatively low weight, good barrier properties and good of weldability. The polyolefin film protects the package from rapid drying or aroma loss while using very little material.

The desire for easy and controllable opening is at odds with consumer demand for hygienic, visually appealing, securely closed, and strong packaging. In the case of packaging made of polyolefin film, easy and controlled opening is criticized by consumers and is considered a disadvantage compared to paper-based packaging.

A uniaxially oriented film exhibits a lower tear resistance in the direction of orientation and can be torn and continued to be torn in this direction without problems and in a controlled manner. But uniaxially oriented films cannot be used in many fields, mainly due to defective mechanical strength in the transverse direction. On the one hand, the biaxial orientation produces the desired high strength (modulus) in two dimensions; on the other hand, however, the preferential directions are thus equalized. This makes it so that in order to open a film package (for example a biscuit bag), first a relatively high force must be overcome in order to tear the film open. But if the membrane ever breaks or cracks, the cracks continue to grow uncontrollably using very low tensile forces. This defective use profile, due to an excessively high tear strength combined with a very low resistance to continued tearing, reduces the acceptance of film packaging on the end consumer market despite the advantages mentioned at the outset.

It is proposed in the prior art to provide predetermined breaking points for the membrane. When opened, the film tears at the predetermined breaking site. But the cracks often continue to grow in a very uncontrollable manner, since this solution, although it facilitates the tearing process, does not contribute effectively to a controlled continued tearing.

Another known possible solution is to mechanically produce predetermined breaking points in the form of openings or scoring along the desired opening line. However, such openings often do not guarantee controlled cleavage either. When opening, the crack follows the perforation line only at the beginning, but then continues at any offset in the material.

This uncontrolled continued tearing behavior is especially problematic in biaxially oriented polypropylene films because the resistance to further tearing is particularly weak in such materials. This problem plays a disturbing role especially in packages with individually packaged goods (Stückgut), which are not loosely but orderly packed, such as packs of cigarette sticks, Weetabix, crackers, Cookie rolls and more. This type of packaging is especially aimed at the situation where the consumer first wishes to remove only a single individual package and wishes to keep the remainder in the package for later removal of other units. For such applications, the uncontrolled further tearing of the film packaging is particularly objectionable to the consumer.

WO 98/2312 describes packaging which is pre-cut by means of a laser beam. The packaging has a multi-layer structure. In particular if a metal intermediate layer is provided, which is supposed to prevent the laser beam from cutting through the film, the packaging is complex and expensive due to the lamination of the metal layer. The exact design of the package is not disclosed in the instructions.

In addition, the perforated film must have sufficient mechanical stability so that the perforated film can be used for packaging individual packaged goods. Methods are described in the prior art in which perforation is integrated as a processing step into the packaging process. This solution avoids a corresponding mechanical loading of the perforated film, eg during winding and unwinding. But the integration of perforation is not feasible for all packaging processes. On the one hand, the spatial conditions in existing installations are usually designed in such a way that there is absolutely no room for retrofitting such installations. Furthermore, the packaging process in the cigarette industry operates at very high speeds, which may be too fast for opening holes. Therefore, it is not always possible to integrate a device for perforating the film into a device for packing cigarette packets into rod packs. A sufficient mechanical stability of the film is at the same time at odds with the desire for easy opening of the packaging.

Contents of the invention

The object of the present invention is to provide improved packaging for ordered individually packaged goods.

The object on which the present invention is based is solved by a package formed from a biaxially oriented film made of polypropylene, which package contains individually packaged goods, wherein the film has at least two perforation lines parallel to each other distributed, and at intervals of a maximum of 10 mm, and the openings of the two lines are arranged offset from each other.

Furthermore, this object is solved by a method for packaging individual packs in which a perforated film is unrolled from a reel and used for packing the individual packs.

Description of drawings

Figure 1 shows an embodiment of a membrane (2) with circular openings (1 ) of length (diameter) B. The length of the spacing between the openings corresponds to the length A. Two parallel perforation lines are arranged at a distance C from one another. In the embodiment according to FIG. 1 , the distance A is exactly as long as the length B of the opening. The perforation lines are arranged offset from one another in such a way that the centers of the individual perforations are aligned with the centers of the opposite intervals.

FIG. 2 shows a membrane with circular openings whose length B is greater than the spacing A. FIG.

FIG. 3 shows an opening with a rectangular geometry, B>A here too.

FIG. 4 shows a membrane with diamond-shaped openings, which were produced, for example, by a rotating knife.

Figure 5 shows a membrane with oval openings. Likewise, B>A here.

FIG. 6 shows a possible geometry of the needle opening, wherein a propeller-like opening is formed.

Figure 7 shows a film web with multiple double perforation lines in the machine direction.

Figure 8 shows an individual wrapper package (3) which is opened by breaking along the double perforation line (4).

Detailed ways

What is common to all these embodiments according to FIGS. 1 to 8 is that the spacing A between the openings is exactly the same as the length B of the openings themselves, or is smaller than the length B of the openings themselves.

Two parallel, offset perforation lines form predetermined breaking points in the film, wherein the crack propagates in a very controlled manner after tearing. After tearing open, the crack continues in a controlled manner along one of the perforation lines or between two parallel perforation lines. The film pack is opened only to the extent desired.

The packaging according to the invention is especially suitable for ordered or stacked individually packaged goods, such as cigarette packets, and for pasty fillings, such as butter, sausages and the like. It becomes possible for the consumer to tear the film along a predetermined predetermined breaking point in such a way that individual individual packages can be removed, whereas in the case of individually packaged goods, other units It didn't fall out uncontrollably. The individual segments between the parallel perforation lines are adapted corresponding to the size of the unit to be removed. It can thus be controlled whether one or more units are conveniently removed by means of a single opening.

The perforation lines can be applied to the film web in a suitable pattern. The lines preferably run linearly. However, the thread can also be applied with any desired geometry, so that the predetermined breaking point then corresponds to the shape and size of the packaged individual packaged goods.

The perforation lines can be produced by mechanical perforation, for example by means of a needle, or a knife, or by means of a laser beam, or otherwise, so that through holes are formed in the film. According to the invention, however, openings are also understood to be thinner locations in which no through holes are produced in the membrane, but the membrane is merely thinned at the corresponding locations by removing material, for example by means of a laser. The beam penetrates only to a predetermined depth. In this embodiment, 10% to 80% of the original film thickness remains in the thinner portion, preferably 20% to 60% of the original film thickness. In this way, a closed package remains obtained which, moreover, is hygienic and does not interfere with the barrier properties of the package.

Alternately following holes, cutouts or thinner points (openings B) along the perforation line are undamaged film sections whose length A is predetermined by the spacing of the perforations. given. In accordance with the invention, a space is thus an area of the undamaged membrane that extends from the end of an opening to the beginning of a following opening on the same opening line.

The geometry of the apertures can vary and is dependent on the aperture method. A needle or a rotating cutter can be used to make the hole. Laser or ultrasound are preferred for perforation lines consisting of non-perforated thinner areas. The needle opening produces a circular shape, or an oval shape, or a propeller shape, which are formed by virtue of the fact that the needle and the membrane come into contact and move relative to each other when opening the hole. Tool openings produce mostly rectangular or diamond-shaped cuts or thinner sections. Laser and ultrasonic methods make different geometries possible. Furthermore, in the case of circular openings, all openings have a greater extent in the direction in which one of the two basic directions is oriented along the opening line (longitudinal direction).

In the aforementioned longitudinal direction, the opening generally has a length B of 0.1 mm to 8 mm, preferably 0.3 mm to 6 mm, in particular 0.5 mm to 3 mm. The extent of the openings transversely to the longitudinal direction is correspondingly small and is generally 5% to 80%, preferably 10% to 50%, of the longitudinal extent of the openings. This does not apply to round openings. Circular and approximately circular openings have a diameter of 0.1 mm-6 mm, preferably 0.3 mm to 5 mm, wherein in this case the diameter corresponds to the length B of the opening.

Particularly preferred for particularly low tearing forces: lengths >1 mm to 6 mm, in particular 1.5 mm to 6 mm, or 2 mm to 4 mm are also suitable. Surprisingly, even in the case of relatively large or long openings, the mechanical strength of the membrane is not hindered. Likewise, this embodiment also allows excellent winding of the film roll and re-unwinding on the packaging machine without problems.

The length A of the section, ie the undamaged membrane between the openings, is 0.05 mm to <8 mm, preferably 1 mm to 6 mm. For longer aperture embodiments such as 1.5 to 6mm, the spacing is preferably >4mm to 10mm. The dimensioning of the space A in relation to the length B of the opening is selected such that the length B of the opening is at least exactly as large or greater than the space A. Typically the length or diameter of the opening is at least 10% greater than the length of the space. The length A of the interval is generally 10% to 90%, preferably 20% to 85%, of the length B of the opening.

The dimensioning given for the openings and spacings also applies to openings in the form of open thinner areas, which can also be circular, oval or It can be shaped into an elongated shape.

The dimensioning of the spacing between the openings is generally constant along the line, or varies only slightly within the range of customary machining accuracy. Likewise, the dimensions of the individual openings are constant along said line, or vary only slightly (up to 10%), ie, for example, the diameter of the hole or the length of the opening is constant. Likewise, the perforations and spacing of the two parallel perforation lines of the predetermined breaking point have approximately the same dimensioning.

It is essential for the invention that the provided predetermined breaking point is formed by two parallel-running perforation lines which are arranged at a distance C of at most 10 mm. Preferably, the interval C between the two lines is 0.5 mm to 8 mm, especially 0.8 mm to 5 mm.

A second feature which is essential to the invention for the predetermined breaking point is the arrangement of the openings of the two opening lines parallel to each other. It was found that the staggered arrangement of the openings of the two lines surprisingly improves the control of the crack propagation. In this offset arrangement, the openings of the second line do not start at the same height as the opposite openings of the first line. Thus, the openings of the second line at least partially overlap the spaces of the first line. In preferred embodiments, especially those in which the openings are larger than the intervals, sections of the perforation line are completely covered by the openings of the opposite line.

In a preferred embodiment, the centers of the segments of the first perforated line are aligned with the centers of correspondingly opposite perforations of the second perforated line, so that a symmetrical perforated pattern results.

Surprisingly, the arrangement of two parallel perforation lines offset relative to each other greatly improves the control of the course of the crack. The invention also makes it possible for the individual packaged goods to It is possible to tear the package at the predetermined breaking point above the edge.

The perforation lines are generally applied in the machine direction of the film. The perforation can be combined simultaneously with the process of cutting the film into narrower film widths and thus performed in one process step. Alternatively, the perforation can also take place before or after cutting to the finished film width. In all variants of this method, the film can be guided, for example, over a roll with a suitable perforating tool, for example equipped with a needle or a blade, for the perforation. During laser or ultrasonic perforation, the corresponding tool is positioned below or above the film web. In this method, the film to be perforated is unwound from a reel, the perforations according to the invention are applied, and the perforated film is subsequently rewound and the reel is placed in a device for packaging individually packaged goods use on. Surprisingly, the perforations do not impede, or only insignificantly, the winding properties of the film, so that the perforated film can be wound and unrolled by means of conventional equipment. It has also surprisingly been shown that the perforations according to the invention do not impair the mechanical stability of the film in such a way that tearing of the film, film breaks, thick spots or stretching occur during winding and unwinding.

The rolls of perforated film are used to produce the packaging according to the invention. The packaging according to the invention is suitable for ordered or stacked individually packaged goods, and especially for pasty fillings such as butter, sausages and the like. It is possible for the user to tear the film along a predetermined predetermined breaking point in such a way that individual individual packages can be removed, whereas in the case of individually packaged goods, other individually packaged goods Did not fall uncontrollably. The individual segments are adapted accordingly to the size of the unit to be removed. It can thus be controlled whether one or more units are expediently removed after the opening process.

Usually a biaxially oriented polypropylene film is used as the film. Depending on the type of packaging, the film may be a translucent to transparent film, or an opaque film. An "opaque film" according to the invention means a film which cannot see through and has a light transmission (ASTM-D 1003-77) of at most 70%, preferably at most 50%. In principle, the membrane can be constructed as a single layer or as a multilayer. Laminates are also suitable for the packaging according to the invention, which laminates are preferably constructed from the films described here.

For a transparent embodiment, the formulation of the film and the type of laser are matched to one another in such a way that the laser beam leaves white or colored lines in the thinned area. As a result, the packaging has a recognizable marking behind it and indicates to the consumer where the cracks for opening the packaging should be distributed in order to facilitate easy handling.

Possible thermoplastics for the film are polyolefins composed of olefinic monomers with 2 to 8 carbon atoms. Particularly suitable are propylene polymers, ethylene polymers, butene polymers, cycloolefin polymers or preferably mixed polymers consisting of propylene units, ethylene units, butene units or cycloolefins. The layer of the film or the layer of the monolayer embodiment accordingly generally comprises, with respect to the weight of the layer, at least 50% by weight, preferably 70 to 99% by weight, in particular 90 to 98% by weight, of thermoplastic polymer.

Propylene polymers are preferred as polyolefins. The propylene polymer comprises 90 to 100% by weight, preferably 95 to 100% by weight, particularly preferably 98 to 100% by weight, of propylene and has a melting point of 120°C or higher, preferably 130°C to 170°C, and Typically at 230° C. and a force of 21.6 N (DIN 53 735 ), 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 is present. Isotactic propylene polymers (with an atactic fraction of 15% by weight or less), copolymers of ethylene and propylene (with an ethylene content of 10% by weight or less), propylene with _C4- Copolymers of C ₈ olefins (having an olefin content of 10% by weight or less), terpolymers of propylene, ethylene and butene (having an ethylene content of 10% by weight or less and having an ethylene content of 15% by weight or less butene content) appear as preferred polypropylenes for the core layer, of which, isotactic propylene homopolymers are particularly preferred. The given weight percentages relate to the corresponding polymers.

Furthermore, mixtures of the mentioned propylene homopolymers and/or propylene copolymers and/or propylene terpolymers and other polyolefins, especially composed of monomers with 2 to 6 carbon atoms, are suitable wherein the mixture comprises at least 50% by weight, especially at least 75% by weight, of propylene polymers. Other suitable polyolefins in the polymer mixture are polyethylenes, especially HDPE (high density polyethylene), LDPE (low density polyethylene), VLDPE (very low density polyethylene) and LLDPE (linear low density polyethylene), where , the proportion of said polyolefins, relative to the polymer mixture, in each case does not exceed 15% by weight.

If necessary, a layer, preferably the base layer or intermediate layer of the film, can additionally contain additional pigments and/or cavitation-inducing particles in the respective customary amounts for opaque embodiments.

The films according to the invention may be monolayer, preferably the films are multilayer. For this purpose, the intermediate layer and/or the top layer can be applied to the base layer on one side or on both sides. Accordingly, the multilayer embodiment of the film has, in addition to the base layer, an intermediate layer and a top layer.

The additional top and/or middle layers are generally constructed of polyolefins. The top layer and/or the middle layer comprise at least 70% by weight, preferably 75 to 100% by weight, especially 90 to 98% by weight, of polyolefin. As polyolefins for this additional layer, the same polymers as described above for the base layer are suitable in principle.

For the top layer, the appropriate

Copolymers of ethylene and propylene, or

Copolymers of ethylene and butene, or

Copolymers of propylene and butene, or

Copolymers of ethylene and another olefin having 5 to 10 carbon atoms, or

Copolymers of propylene and another olefin having 5 to 10 carbon atoms, or

Terpolymers of ethylene and propylene and butene, or

Copolymers of ethylene and propylene with another olefin having 5 to 10 carbon atoms, or

A mixture or blend of two or more of the above-mentioned homopolymers, copolymers, and terpolymers.

Among them, particularly preferred are:

A statistical ethylene-propylene copolymer having an ethylene content of 2 to 10% by weight, preferably 5 to 8% by weight, or

a statistical propylene-1-butene copolymer which accordingly has a butene content of 4 to 25% by weight, preferably 10 to 20% by weight, relative to the total weight of the copolymer, or

Statistically ethylene-propylene-1-butene terpolymers having 1 to 10% by weight, preferably 2 An ethylene content of up to 6% by weight, and a 1-butene content of 3 to 20% by weight, preferably 8 to 10% by weight, or

Blends consisting of ethylene-propylene-1-butene terpolymers and propylene-1-butene copolymers respectively having, with respect to the total weight of the polymer blend:

an ethylene content of 0.1 to 7% by weight, and

a propylene content of 50 to 90% by weight, and

1-Butene content of 10 to 40% by weight.

The aforementioned copolymers or terpolymers generally have a melt flow index of 1.5 g/10 min to 30 g/10 min, preferably 3 g/10 min to 15 g/10 min. The melting point is in the range of 120°C to 140°C. Blends of the aforementioned copolymers and terpolymers have a melt flow index of 5 g/10 min to 9 g/10 min and a melting point of 120°C to 150°C. All previously given melt flow indices are measured at 230°C and with a force of 21.6N (DIN53 735). The layer prepared from the copolymer and/or terpolymer preferably forms the top layer of the sealable embodiment of the film.

The overall thickness of the film can be varied within wide limits and adapted to the intended application. A preferred embodiment of the membrane has an overall thickness of 5 to 250 μm, wherein 10 to 100 μm, in particular 20 to 80 μm, are preferred.

In accordance with the invention, a base layer means a layer which accounts for more than 50% of the total thickness of the film. The thickness of the base layer is obtained from the difference between the total thickness and the applied top layer(s) and intermediate layer(s) and can thus vary within wide limits similar to the total thickness. The top layer forms the outermost layer of the film and is 0.5 to 5 μm, preferably 1 to 3 μm. The intermediate layer is between 1 and 20 μm, preferably 1 to 10 μm.

In order to further improve the defined properties of the polypropylene film according to the invention, the base layer and also one or more intermediate layers and one or more top layers can contain additives in corresponding effective amounts, preferably: hydrocarbon resins and/or antistatic and/or anti-adhesive and/or anti-wear agents and/or stabilizers and/or neutralizing agents, these additives are compatible with the core layer and one or more top layers, but generally incompatible Adhesives are an exception.

Films are produced according to known extrusion methods. Within the scope of the method, the melt corresponding to the individual layers of the film is extruded through a flat nozzle. The film thus obtained is drawn off on one or more rolls and cooled for solidification. The temperature of the one or more pulling rolls is from 10°C to 90°C, preferably from 20°C to 60°C.

Next, the film is biaxially stretched. The biaxial stretching can be carried out simultaneously or one after another, wherein biaxial stretching following one another is particularly advantageous, wherein first the stretching takes place longitudinally (in the machine direction) and then transversely (perpendicular to and its direction) to stretch. In the machine direction, the degree of stretching is preferably from 3:1 to 7:1 and the stretching is carried out at a temperature below 140°C, preferably in the range of 125°C to 135°C. In the transverse direction, the degree of stretching is preferably from 5:1 to 12:1 and the stretching is carried out at a temperature above 140°C, preferably in the range from 145°C to 160°C. The longitudinal stretching is expediently carried out by means of two rollers running at different speeds corresponding to the desired stretching ratio, and the transverse stretching is carried out by means of corresponding clamping frames. In principle, for biaxial stretching, stretching can also be carried out simultaneously in the longitudinal and transverse directions. This simultaneous stretching method is known in the prior art.

For heat setting (heat treatment), the film is then kept at a temperature of 110° C. to 150° C. for a period of about 0.5 s to 10 s. If necessary, one or both surfaces of the film may be corona-treated or flame-treated after biaxial stretching, as described above, according to one of the known methods.

If necessary, the membrane can be laminated, coated, melt-coated, painted or coated by further processing steps after production but before perforation. In order to impart other favorable properties to the film. As the laminated body, a composite body composed of polypropylene and polyethylene is particularly preferable. Such composites can be produced by lamination of individual films. Another technically advantageous variant for producing PP/PE (polypropylene/polyethylene) laminates is the extrusion coating of a suitable polyethylene onto a biaxially oriented polypropylene film. Such extrusion coatings are well known in the prior art. It was found that laminates made of PP/PE films are advantageous in processing with laser beams and are surprisingly less perforable.

The packaging according to the invention is characterized by controlled tearing properties. If necessary, the force necessary to initiate tearing at the film edge can be reduced by scoring (preferably V-shaped). The packaging can continue to tear much easier and more controlled. Furthermore, the packaging according to the invention exhibits all the advantages that are also present in conventional film packaging, such as: high mechanical strength, barrier to water and acid substances, good visual properties.

The packaging according to the invention is particularly advantageous for individually packaged goods, in particular for stacked units such as biscuits, cigarette packets, compressed food preforms.

The film with the perforations according to the invention enables novel packaging solutions for packs of cigarettes, the packets of which are stacked and packed into the film with the perforations according to the invention. The pack of cigarette rods can then be opened at the predetermined breaking point by breaking along the perforation line.

The invention is illustrated in detail by the following examples:

example 1

A transparent, symmetrically constructed, transparent three-layer ABA film with a total thickness of 20 μm was produced in the longitudinal and transverse directions by coextrusion and subsequent graded orientation. The top layer has a thickness of 0.6 μm in each case.

B-Basic:

About 90% by weight propylene homopolymer having a melting point of 162°C and a melt flow index of 3.4 g/10 min

0.15% by weight N, N-bis-ethoxyalkylamine (antistatic agent)

0.30% by weight erucamide

A-top floor:

about 75% by weight statistically ethylene-propylene copolymer with a C2 content of 4.5% by weight

About 25% by weight Statistical ethylene-propylene-butene terpolymer having an ethylene content of 3% by weight and a butene content of 7% by weight (the remainder being propylene)

0.33% by weight SiO ₂ with an average particle size of 2 μm as an antiblocking agent

0.90% by weight Polydimethylsiloxane with a viscosity of 30000 mm ² /s

The manufacturing conditions in each method step are:

Extrusion: Temperature Base: 260°C

Top layer: 240℃

The temperature of the pulling roll: 20°C

Longitudinal stretch: Temperature: 110°C

Longitudinal stretch ratio: 5.5

Transverse stretch: Temperature: 160°C

Lateral stretch ratio: 9

Stereotypes: Temperature: 140°C

Shrinkage (Konvergenz): 20%

Next, the membrane is coated with a sealable acrylate coating.

Next, the film was cut into narrow pieces with a width of 350 mm, and wound up. The narrow section (roll) is guided in a second working step over a roller provided with needles, and here, in the longitudinal direction of the film, is provided with perforation lines arranged in parallel at a distance of 6 mm. The opening has a propeller-like shape with a length B of 4 mm. The spacing between the openings is 2 mm. The film perforated in this way is wound into rolls made of perforated film.

Next, the film thus perforated was used to pack 12 cigarette packets into rods. The packet is arranged such that the edge of the packet is at the level of the perforation line. The packets can be removed by breaking along predetermined breaking sites without uncontrolled crack propagation in the film.

Comparative example

On the film described in Example 1, a single row of perforations was provided by means of needle rollers of the same type. The openings have the same length and the same spacing as in Example 1. The film was used in the same manner to pack 12 cigarette packets into rods. The package cannot be opened by breaking. In tests where the film was torn along the perforation line, in 3 out of 10 tests, uncontrolled continued tearing occurred alongside the perforation line.

Claims (9)

1. A biaxially oriented film reel made of polypropylene with perforated lines, characterized in that the film has two perforated lines running parallel to each other and at a maximum distance of 10 mm In the interval, and wherein, the openings of the two lines are arranged staggered from each other, wherein the two lines of openings distributed in parallel and arranged in a staggered manner form a predetermined break in the film, and the openings between the two lines The intervals are spaces formed by undamaged film, and the length of the spaces between these openings is 20% to 85% of the length of the openings, and wherein the length of the openings is 2 mm to 4 mm and is Rhomboid or rectangular, wherein the width of the openings is 10% to 50% of its length, and wherein the thickness of the membrane is 20 to 80 μm. 2. A roll of polypropylene film according to claim 1 , wherein the film is multilayered. 3. The roll of polypropylene film according to claim 1, characterized in that the openings are produced by means of a knife. 4. The roll of polypropylene film according to claim 1, characterized in that the opening is a thinner part having 10% to 80% of the remaining film thickness. 5. The roll of polypropylene film according to claim 1, characterized in that the openings are cutouts or thinner film portions. 6. The roll of polypropylene film according to claim 1, wherein the centers of the segments of the first perforated line are aligned with the centers of the corresponding opposed perforations of the second perforated line. 7. Use of an apertured film reel according to claims 1 to 6 for packaging cylindrical or square individually packaged goods. 8. Use according to claim 7, characterized in that the individually packaged goods are cigarette packs. 9. Pack of cigarette rods manufactured by the use according to claim 8.