EP1357054A1 - Microwavable food package having a peelable lid and venting valve - Google Patents

Abstract

A food packaging which can be microwaved, comprises a lower section for holding the food (100), a sealed lid film (110), and at least one valve (120) incorporated in the lid film. The valve relieves pressure that builds up during heating. The film has a peel force of 4-20 N/15mm, preferably 7-14 N/15mm, especially 8 N/15mm, and consists of a PET - PP laminate, where the PP layer acts as the sealing layer (140) and the PET layer is the upper layer (130).

Description

FIELD OF THE INVENTION

The present invention relates to a microwave-capable Food packaging with a peelable lidding film.

BACKGROUND OF THE INVENTION

Food packaging has long been known in which the Food is packed in a thermoformed pack, which with a sealable, i.e. welded cover film is closed. Furthermore, it is known that the sealable lidding film is designed so that it is peelable, i.e. that it can be withdrawn from the thermoformed pack in order to move onto the Access to food. Such a film is for example described in DE 44 10 235 C2.

Thermoformed packs with sealed lidding film have been around for some time also used for microwaveable food, although here additional problem occurred that in the microwave during the cooking process Overpressure arises, which must be released to the outside. Has been for some time However, this problem was also solved by incorporating a valve in the cover film is, which derives the resulting excess pressure to the outside. Such Microwave-compatible food packaging is described, for example, in EP 0 971 849 B1.

In the known microwavable packaging with sealed Cover film, however, has the problem that this film is not peelable. Since in During the cooking or cooking process, relatively high pressures (up to approx. 1 bar overpressure) arise and temperatures of up to 120 ° C prevail, the Cover film to be comparatively resistant, so the package when cooking Cooking process does not burst.

An object of the present invention is therefore a to create microwave-compatible food packaging, which with a peelable cover film is provided and yet the comparatively extreme Conditions of the cooking process withstands.

SUMMARY OF THE INVENTION

According to a first embodiment, the present comprises Invention a lower packaging part for holding food, which with a sealed cover film is provided, at least in the cover film a valve is incorporated, which is used to derive the Microwave cooking process resulting overpressure is used, the cover film a peel force between 4 and 20 N / 15 mm, preferably between 7 and 14 N / 15mm, in particular 8 N / 15mm.

According to a preferred embodiment, the cover film is made made of a PET-PP composite, with the PP layer as the sealing layer. The Layer thickness of the PET layer is between 10 and 16μ, preferably this 12µ. The layer thickness of the sealing layer is preferably between 70 and 110µ, particularly preferred are 90µ.

According to a further exemplary embodiment, instead of PET also an oriented polyamide (OPA) with a layer thickness between 10 and 20 µ, preferably with a layer thickness of 15 μ, can be used.

According to a preferred embodiment, the Bottom side of the sealing layer facing the packaging with an anti-fog solution coated to prevent fogging of the lidding film.

According to a preferred embodiment, the peeling force is sealable film before the antifog coating, at 9 to 12 N / 15mm, preferably at 10 N / 15mm. The peeling force is then through the coating somewhat reduced to about 8 N / 15mm.

According to a further exemplary embodiment, the peeling force is one film not coated with antifog solution between 7 and 10 N / 15mm, preferably at 8 N / 15mm.

According to a preferred exemplary embodiment, the valves of the cover layer that are used are valves whose total hole cross-sectional area is sufficient to dissipate the overpressure arising in the course of the cooking process sufficiently quickly. For this, an adaptation of the total area of the one or more outlet holes of the valve or of the valves used is crucial. The total hole cross-sectional area is preferably at least 12 mm ² , more preferably more than 21 mm ² . According to a particularly preferred exemplary embodiment, the total hole cross-sectional area of the valve used is between 23.2 and 23.3 mm ² .

The present invention will now be described in several Embodiments with reference to the accompanying drawings in Described in detail.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

shows schematically a valve packaging with sealable and peelable lidding film according to a first Embodiment of the present invention.

2A-2H

schematically show examples of valves used in the valve packaging according to the invention for use can come.

DETAILED DESCRIPTION

1 schematically shows a microwave-capable packaging according to a first embodiment of the present invention. On the dashed The drawn lower part of the packaging is the sealable and peelable one Cover film 110 sealed, in which the valve 120 is sealed. As in Fig. 1 indicated, the cover film 110 consists of two laminated layers 130 and 140, the top layer 130 being thinner than the bottom Seal layer 140.

According to the first embodiment, the Sealing layer around a peelable layer based on polypropylene (PP) with a Thickness of 90µ. The upper layer 130 is a PET layer with a thickness of 12μ, which is laminated to the lower sealing layer 140.

It is crucial that the sealed composite film is designed with regard to its peeling forces in such a way that it can withstand the temperatures and pressures that arise during the microwave cooking process and is nevertheless peelable after the cooking process has been completed. In the first exemplary embodiment of the present invention, to achieve this purpose, a special film is used as the sealing film 140, the peeling force of which is 8 N / 15 mm ² . It is a polypropylene-based film that is particularly heat-resistant and whose peel forces are suitable for the pressures generated during the microwave cooking process. A film which is suitable as a sealing layer in accordance with the first exemplary embodiment is, for example, the film with the name PROPEEL-100 from KWH Plast Ltd., Finland. This sealing layer is then laminated to a composite film with a PET top layer. The layer thickness of the sealing layer is 90µ, the layer thickness of the top layer, which in this embodiment is a PET layer, is 12µ.

It is clear to the person skilled in the art that certain modifications of the Thickness of the individual layers are possible, provided the resulting peel forces and the peel properties are still reasonable for the purposes Application.

For example, in a further exemplary embodiment The top layer of the cover film can be formed from an OPA, the thickness of which is between 10 and 20 μ, preferably 15 μ.

As already mentioned, a valve 120 is incorporated in the cover film, that serves to derive the resulting excess pressure. This valve will now be short described with reference to Fig. 2A. Further descriptions of the The basic function of this valve can be found, for example, in DE 198 43 430 A1 and in EP 0 069 264 B1.

2A shows a first example of a valve in a top view. The valve body 300 has a hole 310 in the center, extending from the hole 310 there is a support surface 320 for supporting a membrane up to a flange 330, which means attaching the valve e.g. on one package.

The membrane is prevented from falling out of the valve body through the web 350, which over the contact surface between the opposite Side of the side wall of the valve is attached and by a clamping force is held.

FIG. 2B shows a section through the valve shown in FIG. 2A. In the 2B is next to the support surface 320 and the flange 330 the side wall 325 of the valve body is also easy to recognize. Next to it is in Fig. 2B also the membrane 340 shown, which rests on the support surface. It is a sealing oil 335 between the bearing surface 330 and the membrane 240 provided that ensures that the hole 310 is hermetically sealed.

The web 350 is between the side walls 325 of the valve body attached and is to ensure that the membrane 340 is not out of the Valve body can fall out.

As can be clearly seen in FIG. 2A, the valve has one comparatively large hole in the middle of the valve support surface. The bridge 350 is dimensioned so that it does not completely cover the hole. The Dimensioning of the web can also be such that the hole is completely covered if the web 350 is as in the sectional view of FIG Fig. 2B shown does not exert any contact pressure on the membrane. The bridge practices you direct contact pressure on the membrane, but it is preferred if the Web is not located completely over the perforated surface to allow air to escape through the hole and thus not to prevent a reduction of the excess pressure.

2C shows another example of a valve. Are in this Example, a total of four holes 310 are provided, each in the same radial Distance from the center of the valve are arranged. The four holes are there arranged symmetrically, i.e. is the distance between two adjacent holes always the same. In the view of FIG. 2C it can be seen that the web 350 is different is located just between the holes and this ensures that it exits the pressure is not hindered by any of the holes. The holes are in the formed essentially in the form of equilateral triangles, the corners of the Triangles are slightly rounded. This shape of the holes is a special one effective reduction of overpressure with good pressure at the same time Reclosure characteristics of the valve can be achieved.

A cross-sectional view of the valve of FIG. 2C is shown in FIG. 2D. The web 350, the membrane 340 and the sealing oil 335 are also good here recognize.

Finally, FIGS. 2E and 2F show a further variant of a Valve for a microwave-compatible food packaging. Due to the odd number of holes is necessarily at least always one of the Holes are at least partially covered by the web, as is also the case in FIG. 2F is recognizable.

Another variant of a valve used is shown in Fig. 2G shown in a top view. The total of five holes are there as something curved elongated holes formed. The cross-sectional view (not shown) corresponds to that shown in FIG. 2D or FIG. 2F depending on the section line.

The hole shape of the valves shown in FIGS. 2A to 2G can be seen in further exemplary embodiments, which are not represented graphically here, for example, assume a circular shape. There are also more than five holes basically conceivable. In a preferred embodiment, the valve however at least three, preferably five holes. According to another As shown in FIG. 2A, the embodiment is also a valve with only one Hole possible.

The total perforated area is decisive for the use as a pressure valve in a microwave cooking process. In the case of the valve of FIG. 2A, this is 23.24 mm ² , for the valve from FIG. 2C it is 23.25 mm ² , for the valve from FIG. 2E it is 23.20 mm ² and for the valve from FIG. 2G it is 23 , 28mm ² . The skilled worker is clear that certain modifications of the total hole area are possible, preferably the total hole area is, however, at least 12 mm ^2, particularly preferably more than 21mm ^2, more preferably more than 23mm. ²

According to a further embodiment, the peelable Cover film 110 via an anti-fog property, i.e. the The surface properties of the lidding film are changed so that they are on the inside the packaging does not form droplets that block the view of the food could block. For this purpose, the one facing the food Provide an anti-fog solution on one side of the cover film to create a To prevent droplet formation. A particularly suitable anti-fog solution for this is under the designation 15-029331-4-DFC from Siegwerk, Germany, available. Since applying the anti-fog solution to achieve The antifog properties change the peel forces of the film Embodiment used as a sealing layer, a film that initially something has higher peel forces, preferably about 2N / 15mm more than that not Foil provided with an antifog solution. The peeling force is therefore included for the sealing film this embodiment at 10 N / 15mm. After coating, the sinks Peel force to about 8 N / 15mm. One for this embodiment as a sealing layer 140 particularly suitable film is from the GS Retopeel GS Technologies, Fintshire, Great Britain.

The sealing layer then becomes one with a PET top layer Laminated laminate. The thickness of the sealing layer 140 is the same Embodiment likewise 90μ, also the thickness of the upper PET layer 130 is unchanged at 12µ. Here too, however, it applies that these modifications of the Layer thicknesses are possible for the person skilled in the art, provided the resistance against pressure and temperature is still sufficient and the peel forces in the reasonable framework.

In this embodiment, too, valves according to FIGS. 2A-2G are used.

With the described in the described embodiments Invention a microwave-compatible food packaging is created that is not only suitable for the microwave, but also special for the user has high ease of use, since the lid film used is peelable and nevertheless the pressures that arise during the microwave cooking process and withstands temperatures and also regulates them.

Claims (8)

Microwave-compatible food packaging, which has: a lower part of the packaging for holding food; a cover film sealed on the lower part of the packaging; at least one valve incorporated in the cover film for discharging the overpressure arising in the microwave cooking process, the cover film having: a peel force between 4 and 20 N / 15mm, preferably between 7 and 14 N / 15mm, in particular 8 N / 15mm. Food packaging according to claim 1, wherein the lidding film comprises: a PET-PP composite, with the PP layer as the sealing layer. Food packaging according to claim 1, wherein the lidding film comprises: an OPA-PP composite, with the PP layer as the sealing layer. Food packaging according to claim 1 or 2, wherein the cover film comprises: a sealing layer with a layer thickness between 70 and 110µ, preferably between 80 and 100µ, in particular 90µ; and a layer thickness of a further layer of PET applied to the sealing layer between 10 and 16μ, preferably between 11 and 13μ, in particular 12μ. Food packaging according to claim 1 or 3, wherein the cover film comprises: a sealing layer with a layer thickness between 70 and 110µ, preferably between 80 and 100µ, in particular 90µ; and a layer thickness of another layer of OPA applied to the sealing layer between 10 and 20μ, preferably between 13 and 17μ, in particular 15μ. Food packaging according to one of the preceding Claims in which the side of the packaging base facing the Sealing layer is coated with an anti-fog solution to prevent fogging prevent. Food packaging according to claim 6, wherein the peel force of the sealable film before the anti-fog coating between 9 and 12 N / 15mm, is in particular 10 N / 15 mm. Food packaging according to one of the preceding claims, in which the total cross-sectional area of the outlet holes of the valve or valves incorporated into the cover film is at least 17 mm ² , preferably more than 21 mm ² , in particular more than 23 mm ² .

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