EP1793987A2

EP1793987A2 - Material web for packagings, and packaging containers

Info

Publication number: EP1793987A2
Application number: EP05792980A
Authority: EP
Inventors: Alfred Remmele; Roland Limbeck; Bernhard Lang
Original assignee: Suedpack Verpackungen & Co GmbH
Current assignee: Suedpack Verpackungen & Co GmbH
Priority date: 2004-09-29
Filing date: 2005-09-19
Publication date: 2007-06-13
Also published as: WO2006034793A3; US20090029082A1; WO2006034793A2

Abstract

The invention relates to a material web consisting of at least two superimposed films (14, 15). According to the invention, slit-type recesses (17) are integrated into the film (15) forming the outer side of a packaging container (11), said recesses being at a distance from each other, and the film (14) carrying the outer film (15) is produced from a material which can be deformed in such a way that it is approximately axially perpendicular to the recesses (17). The inventive embodiment enables the material web formed by the films (14, 15) to be used in food packagings in which an excess pressure produced is to be dissipated in a controlled manner. The recesses (17) grow namely according to the inner pressure, and pore-type openings form in the packaging (11) and in the inner film (14) such that the excess pressure can automatically dissipate. The bursting of the packaging container (11) during the pasteurisation of the food (20) contained therein is thus almost excluded.

Description

Material web for packaging as well as packaging containers

The invention relates to a material web which is composed of at least two superimposed films and from the lid films for packaging containers or packaging bags, for example, are produced and on a film packaging for food with pressure relief valve, formed by a self-opening at a certain pressure inside Weak zone and to a method for producing a foil packaging according to the preamble of claim 18.

EP 1 359 097 A1 discloses a package for foods to be subjected to a pasteurization process. The food enclosing the food airtight in this case is provided with a valve in order to be able to deliver at least partially to the environment caused by the heating of the food pressure in the packaging.

Although such packages have been proven for some time, the onset of separately prepared valves in the packaging but associated with a considerable amount of work. In addition, the valves consist of several components, such as a membrane held by webs, between which and the sealing body, a sealing oil is applied, so that damage during transport of the packaging and disturbances in the pasteurization process are almost unavoidable. A film packaging known from DE 102 53 916 A1 consists of a tubular bag with a welded seam. In this at least one un welded area is provided, which comes close on one side close to the interior and on the other side is in communication with the outside space. The steam produced during heating, for example, by microwaves in the tubular bag leads to a rise of the welded seam on the way of the unwelded region, so that in this way an automatically opening pressure relief valve is formed. By suitable design, for example, tapered shape, the outlet cross-section for the vapor is kept relatively small, so that even steam pressure is maintained in the tubular bag. However, this weakening in the area of the sealed seam causes no high pressure to be generated in the bag; This requires a longer cooking time and leads to a collapse of the bag after switching off the microwave oven.

Another steam cooking bag for microwave use, which is described in DE 41 22 077 A1, can be closed by means of closure clip and has on one side a group of stamped or pierced perforations. During cooking, the vapor pressure swells up the top of the bag so that the overpressure is vented through the perforation. Again, the pressure is not very high and after switching off the micro-device it also comes to collapse of the bag.

In a food package described in DE 695 23 751 T2 a slot is provided in a film web, which is covered by a peelable membrane. By peeling off the adhesive membrane, the slot can be exposed without opening the package. This is done automatically in a microwave oven, where due to the pressure increase the adhesive membrane is raised and then through the slot can be done a vent. The construction of a vapor pressure in the packaging is not provided. During production, a cutting and a gluing process are additionally required, which increases the production costs. Another method for equalizing the overpressure during cooking of ready meals is to use the so-called basement valve, which is a plastic part inserted into a bag. In this there is a small foil blank with slot and a closed foil blank. When the vapor pressure builds up in the bag, the first blank is lifted off and the vapor pressure can escape in a defined manner across the slotted blank. A disadvantage of this method is the very high cost of the use of plastic, and therefore the basement valve is currently ver¬ used only for large bags for commercial kitchens or for very high quality ready meals. Also, the assembly of the plastic insert itself is very expensive, so that this is not suitable for mass products, ie with a single use of the valve, the costs can not be covered.

The film processing by means of laser beams is known. Thus, according to EP 0 540 184 A1, a score line has already been introduced by means of a laser in a plastic packaging in order to be able to open it more easily. Even with a known from DE 697 11 704 T2 food packaging with a light metal middle layer a pre-cutting line produced by laser is provided.

The object of the invention is therefore to provide a material consisting of at least two superimposed films web, which can be used for the production of packaging in which stored foods are subjected to a pasteurization process, without the need for separate pressure relief valves. The production of the material web should be possible in a simple and very economical manner, but should be reduced controlled controlled during heating of the stored food pressure and packaging should automatically close after the degradation of the overpressure again almost airtight.

It is a further object of the invention to provide a film package which allows food to be cooked in a microwave oven under the highest possible pressure for a sufficient period of time. According to the invention, the material web composed of at least two superimposed films, by means of which this can be achieved, is characterized in that one or more slot-like recesses are incorporated in the film forming the outside of a packaging container or a packaging bag. or transverse direction of the packaging container or the packaging bag are arranged laterally spaced from each other, and that the provided with cut-away film foil or films are made of an at least approximately axially perpendicular to the slot-like recesses elastically deformable material.

Furthermore, this object is achieved by the invention in a film packaging with the features of claim 8. A method for producing a film packaging is specified in claim 19. Advantageous developments of the film packaging according to the invention and of the production process are the subject matter of the subclaims.

It is expedient here to produce the foil provided with the cutouts from a biaxially oriented material, but it is also possible if this foil consists of a monoaxially oriented material which is elastically deformable in the axial direction of the cutout.

According to another embodiment, however, the material web can also be produced from a coextruded multilayer film in which the outside of a packaging container or a bag-forming layer, the recesses are incorporated.

It is very advantageous to incorporate the slit-like recesses by means of a laser beam into the outer film or layer of the material track, preferably during their production. The biaxially or monoaxially oriented or coextruded material film of the material web may consist of polyester, polyamide, polypropylene or polyamide-Ethylenvinylakohol polyamide or another film composite with an embedded layer of ethylene vinyl alcohol with a layer thickness of about 10 - 40 microns; the elastically deformable film of the material web can consist of coextruded polypropylene or polyethylene with a layer thickness of about 30-100 μm.

If a material web is formed according to the invention, it is possible to use it wholly or partly in packaging, in particular for foodstuffs, in which a controlled excess pressure is to be reduced in a controlled manner. By virtue of the fact that one or more recesses are incorporated in the outer film which increase in dependence on the internal pressure of the packaging, and the foil carrying the latter consists of an elastically deformable material in which pore-like openings form during expansion, it is possible for itself reduce the overpressure in the packaging. The choice of materials, the arrangement and / or the length and / or design of the recesses may be used to tune the limits of overpressure, e.g. be adjusted to the respective pasteurization process and the stored food.

Since, in order to make this possible, no separate components are required, the operation rather results from the selected materials, an extremely high reliability is guaranteed. Furthermore, the production of the web can be accomplished with very little effort. Namely, the recesses can be incorporated directly in the outer layer, eg by means of a laser beam, in the production of the material web, so that an additional operation is not required. With the aid of the material web designed according to the proposal, packaging containers and bags can thus be manufactured inexpensively, in particular for foods to be subjected to a pasteurization process, which enable pressure reduction at high operational reliability and thus do not burst open, wherein the barrier properties of the web are not significantly affected by the slot-like recesses.

In the case of a foil packaging according to the invention for foods, a pressure relief valve is thus provided which is formed by a weak zone which automatically opens at a certain pressure inside. The film package comprises at least two film layers, one of which comprises a laser-generated perforation formed by dots and / or lines, while the other is closed there. That is, the laser used for cutting is wavelength and power adjusted and controlled to maintain a position that seals the food package. In the other film layer, the perforation forms a weakening of the packaging at this point. When the food is warmed up, evaporation of water within the packaging increases pressure. It then opens the perforation line, which may for example be a slot, and the other film layer, e.g. the sealing layer is stretched with increasing pressure. Overstretching then results in the formation of several small openings and cracks in this film layer, i. if the elastic limit is exceeded, a break of the film occurs. The overpressure can escape via the small openings thus formed and a balance is established between the resulting overpressure and the number or opening size of the holes in the film.

In this case, the phenomenon still occurs that in the edge region of the holes formed in the second film, the material still has an elasticity and thereby partially close or become smaller again when the pressure inside the film packaging decreases again. The pressure relief valve thus formed is therefore a dynamic valve which opens depending on the pressure and closes again to a limited extent. In this way it is possible that during the cooking of pre-packaged prepared meals in the microwave controlled steam can escape, whereby the dynamic behavior over the cooking time, a greater pressure can be maintained and the cooking time is reduced. The valve effect is independent of the size of the package or the content, whether the water content eg 30 ml or 300 ml. When the microwave is switched off again, the pressure inside the film packaging is slowly reduced. Unlike conventional film packaging with holes, film packaging does not collapse, as is well known in pouch packaging.

Through the use of laser technology, the provision of the perforation according to the invention can be used very easily without additional additional costs in mass production. This process can be integrated without additional work steps in the existing process technology, for example in the form of an integration on a slitter.

In principle, a specific wavelength can be used in the inventive formation of the perforation in the film layer. In this case, the prerequisite is that the film layer provided for the perforation in the film composite consists of a film absorbing the wavelength typical for the laser. For example, a PET film at 10.25 microns well absorbed the laser light for the formation of perforations. The absorbent film layer may also be the bottom film layer, i. the laser beam passes through the overlying first layer and is separated in the underlying second layer due to the higher absorption. By choosing the wavelength, the desired location, i. E. the film layer to be perforated are selected.

The perforation may be in the form of dots and / or lines. For example, it may be a slot or a line consisting of very short lines or points, wherein the intermediate webs must be chosen so small that they break when stretching the film and not counteract the actual valve effect. It can also be provided several perforations (slots, lines, etc.), the contour can be chosen arbitrarily. The length of the slots, for example, is determined by the physical properties of the film layer to be stretched, ie the elastic limit determines the breakage of the film. If the slot is too short, it will not overstretch the film, this does not break, it there is no valve effect and the packaging bursts. For example, slits with a length of 30 mm were introduced into the one film layer. Other slot lengths are also possible and also depend on the film dimensions. On the other hand, the slot can also be made to the complete line over the entire package. However, this can lead to the disadvantage that the stability of the packaging is greatly impaired and the barrier properties of the packaging are thereby influenced too much. The width of the slots can also be adjusted specifically to different, arbitrarily selected dimensions, for example by defocusing the laser or by means of a collimator. Preferably, the slit width is 0.1 to 3 μm, more preferably 1 to 3 μm.

In an advantageous embodiment of the invention, the film is a duplex film with two layers, wherein the sealing layer, for example, polypropylene or polyethylene and the protective film may be, for example, biaxially oriented polyamide, polyester and SiO _x -coated polyester or monoaxially oriented vinylpolyamide, etc. As laser, a CCV laser has been used, although other lasers can also be used.

In the drawing, a trained according to the invention material web and their use in packaging containers are shown, which are explained in detail below. Hereby shows:

Figure 1 is a provided with slot-like recesses web, in

Top view,

2 shows the material web of Figure 1 in a section along the line II - II, in enlarged scale,

FIG. 3 shows a packaging container closed with a material web formed according to FIG. 1, in a section, FIG. 4 shows the packaging container according to FIG. 3, in the overpressure state,

Figure 5 is a plan view of the lid film of the packaging container of Figure 4, in an enlarged view, and

FIG. 6 shows a packaging bag produced from the material web according to FIG.

FIG. 7 (a) is a schematic sectional view of a duplex film package according to the invention; and (b) is a plan view of a detail of the package, illustrating the insertion of the slot.

8 shows an illustration of the opening process by increasing pressure with elongation of the perforated film (a) in section and (b) in plan view, in the packaging according to FIG. 7, FIG.

9 shows an illustration of the overstretching process of the perforated foil (a) in the sectional view and (b) in plan view, in the packaging according to FIG. 7, FIG.

FIG. 10 is a sectional view similar to FIG. 7, but with the underlying film cut;

Figure 11 Examples of different Perforationsausführungen according to the invention to 14 invention.

The material web shown in FIGS. 1 and 2 and denoted by 1 can be used, for example, according to FIG. 3 as lidding foil sealable onto a packaging container 11 or as packaging pouch 21 according to FIG. 6 and consists of an inner foil 2 and an adhesive layer 4 with the latter The outer film 2 is hereby made of an elastically deformable material, the outer film 3, however, in the embodiment shown from a biaxial material.

Furthermore, slot-like successively spaced recesses 5 are incorporated into the outer film 3, but according to the dot-dashed representation it is also possible to provide two or more rows of slot-like recesses 5 'in the outer film 3 next to one another.

The slot-like recesses 5 can, as shown in FIG. 2, be incorporated into the outer film 3 during the production of the material web 1 with the aid of a laser beam 10 'supplied via a laser head 10. The thereby removed material of the outer film 3 is sucked by means of a blower, not shown.

According to FIG. 3, a cover film 13 is sealed on the peripheral edge 12 'of the packaging container 11 formed as a shell 12, which can be worked out of the material web 1 and consists of an inner film 14 and an outer film 15 which are fixed together by means of an adhesive layer 16 are connected. The outer film 14 in turn has slot-like recesses 17.

When the food stored in the packaging container 11 is heated by a pasteurization process, the internal pressure in the packaging container 11 increases, and the lid film 13 is expanded as shown in FIG. In this case, the slit-like recesses 17 incorporated into the outer film 15 open, since the film 15 is designed to be non-stretchable. In contrast, in the inner elastically deformable film 14, a plurality of pore-like through-openings 18 are formed, via which the overpressure prevailing in the packaging container 12 is reduced in the region of the cutouts 17, in which air can flow out. However, as soon as the pressure in the packaging container 11 is lowered, the lid film 13 is automatically returned to the initial state due to the elasticity of the inner film 14, so that the packaging container 11 is in turn closed almost airtight. In the same way, the packaging bag 21 produced from a tubular film and sealed by a sealing seam 22 according to FIG. 6 is effective. The inner film 23 is made of an elastically deformable material, on the other hand, the film 24 arranged on this again biaxially designed and provided with slot-like recesses 25. The stored in the packaging bag 21 food 30 can thus be cooked without it being feared that ruptures due to excessive pressure of the packaging bag 21.

FIG. 7 shows the introduction of a slit 110 into the upper foil 101 of a duplex foil F by means of a laser beam L. In the course of the heating, evaporation of water occurs in the foil packaging and thus an increase in pressure, whereby the slit 110 of the foil 101 opens.

This is illustrated in FIG. As a result of the inflation of the package, the slot 110 of the film 101 is widened and the underlying film 102 is stretched. A local dilution 112 forms. As a result of the pressure increase, the film 102 is overstretched. Small openings 114 form when the elastic limit is partially exceeded, and the film 102 breaks. The formation of the openings 114 is illustrated in detail in FIG. 9 (b).

Figure 10 shows a similar arrangement but with the underlying film 102 being cut and the film 101 forming the protective film.

FIG. 11 shows a perforation line which extends over the entire film 101 but consists of individual slots.

FIG. 12 shows an arrangement of arbitrarily arranged slots 110 '. FIG. 13 illustrates that the shape of the slots 110 "or perforations can be arbitrary, for example curved, zigzag-shaped, circular-arc-shaped, bent-off, etc.

Figure 14 illustrates slots 10 "formed of individual line sections. It can thus be seen that the contour of the lines and slots as well as their location may be arbitrary.

Claims

claims

1. material web (1) which is composed of at least two films (2, 3) arranged one above the other and from which, for example, cover films (13) for packaging containers (11) or packaging bags (21) can be produced,

characterized,

in that in the outside of a packaging container (11) or a packaging bag (21) forming film (3, 15, 24) one or more slot-like recesses (5, 5 ', 17, 25) are incorporated, which in longitudinal and / or Transverse direction of the packaging container (11) or of the packaging bag (21) are arranged with a lateral distance to each other, and that the with the recesses (5, 5 ', 17, 25) provided film (3, 15) carrying foil (2, 14, 23 ) or films are made of a material elastically deformable at least approximately axially perpendicular to the slot-like recesses (5, 5 ', 17, 25).

2. Material web according to claim 1,

characterized, in that the foil (3, 15, 24) provided with the cutouts (5, 5 ', 17, 25) consists of a biaxially oriented material.

3. Material web according to claim 1,

characterized,

in that the film (3, 15, 24) provided with the free racks (5, 5 ', 7, 17, 25) consists of a monoaxially oriented material which can be elastically deformed in the axial direction of the cutout (5, 5', 17, 25) is.

4. Material web according to claim 1,

characterized,

in that the material web (1) consists of a coextruded multilayer film in whose outer side of a packaging container (11) or a bag (21) forming layer the recesses (5, 5 ', 17, 25) are incorporated.

5. Material web according to one or more of claims 1 to 4,

characterized,

the slot-like recesses (5, 5 ', 17, 25) are incorporated by means of a laser beam (10') into the outer film (3) or layer of the material web (1) during their production.

6. Material web according to one or more of claims 1 to 4, characterized,

in that the sheet (3, 15, 24) of biaxially, monoaxially oriented or coextruded material of the web (1) consists of polyester, polyamide, polypropylene or polyamide-ethylvinyl alcohol-polyamide or another film composite with an embedded layer of ethylenevinyl alcohol with a layer thickness of about 10 - 40 microns exists.

7. Material web according to one or more of claims 1 to 4,

in that the elastically deformable film (2, 14, 23) of the material web (1) consists of coextruded polypropylene or polyethylene with a layer thickness of about 30-100 μm.

8. film packaging for food with pressure relief valve, formed by a starting from a certain pressure in the interior automatically opening weakness zone (110),

characterized,

the film packaging comprises at least two film layers (101, 102), one of which comprises a perforation (110) formed by laser (L) and formed by dots and / or lines, while the other is closed there.

9. film packaging according to claim 8,

characterized,

in that a slot (110) is provided as a perforation.

10. film packaging according to one of claims 8 or 9,

characterized,

in that the perforation is a line (110 '") consisting of short lines or points.

11. Film package according to claim 8,

characterized,

a plurality of perforations (slots, lines) (110 ', 110 ", 110'") are provided.

12. Film package according to one of claims 8 to 11,

characterized,

a film layer is a sealing layer (102) and a film layer is a protective film (101).

13. Film package according to claim 12,

characterized,

the protective film (101) is made of polyethylene terephthalate (PET), vinylpolyamide (VPA), polyalphaolefin (PAO), SiOx-coated poly (terephthalate) (PET / SiOx).

14. Film package according to one of claims 8 to 13,

characterized, a film layer is made of polypropylene or polyethylene.

15. Film package according to one of claims 8 to 14,

characterized,

a film layer is made of biaxially oriented polyamide, polyester and SiOx-coated polyester or monoaxially oriented vinylpolyamide.

16. Film package according to one of claims 8 to 15, •

characterized,

the film layers form a cover film or a lid.

17. Film package according to one of claims 8 to 16,

characterized,

that the packaging is a bag formed from the two film layers.

18. Material web or film packaging according to one or more of claims 1 to 17,

characterized,

the perforation or slot width is 0.1 to 3 mm, in particular 1 to 2 mm.

19. A method for producing a film packaging for food to be cooked, in which a self-starting from a certain pressure inside Weak zone is introduced into the film,

characterized,

in that two film layers (101, 102) are used, of which one generates a perforation (110) formed by laser light (L) of dots and / or lines.

20. The method according to claim 19,

characterized,

in that the wavelength and / or the power of the laser (L) for the production of the perforation (110) is set in a specific one of the two film layers.