WO2007012468A2

WO2007012468A2 - Reclosable microwave-suitable packaging

Info

Publication number: WO2007012468A2
Application number: PCT/EP2006/007345
Authority: WO
Inventors: Friedrich Kastner; Stefan Zoister; Gyula Madai
Original assignee: Mondi Packaging Ag
Priority date: 2005-07-27
Filing date: 2006-07-26
Publication date: 2007-02-01
Also published as: CY1110110T1; WO2007012468A3; PT1912865E; EP1912865A2; EP1912865B1; ATE465098T1; DK1912865T3; US20100276327A1; SI1912865T1; ES2342845T3; PL1912865T3; DE502006006808D1; AT502215A1; CA2617078A1

Abstract

The invention relates to a packaging suited for heating in microwave ovens, ovens or double boilers, which is comprised of a multilayer film material having at least one area that is rendered permeable when an internal pressure generated by the microwave heating is exceeded. The invention is characterized in that this area is formed by a microperforation that is covered by a label or by a hot stamping film or by a varnish coating.

Description

Reclosable microwaveable packaging

The invention relates to a package for food, ready meals, animal feed, non-food products, such as cold-hot packs, packaged refreshment wipes, detergents, cleaning agents and the like, which is suitable for use in the microwave, in the oven or in a water bath.

Food or ready meals, which are heated in a package, in particular in a microwave oven or an oven or a

Water bath, are known.

Packaging is understood to be rigid, semi-rigid or flexible packaging.

Such packages tend due to the expansion of the contents and the expansion of air and associated with the heating

Gases burst or burst.

To a limited extent, this risk can be mitigated by using

Packaging that is significantly larger in size than the volume of the

Fillings, be reduced.

Furthermore, the water present in the product is converted into steam when heated. This steam can be sealed by the usual

Packaging is difficult or impossible to escape, so it is not crispy

Heating of ready meals possible.

From EP 661 219 B1 a packaging is known, which has a multilayer construction. The outer layer and the inner layer are heat-fusible merge together. Further, there is provided a connecting part by which the outer layer is connected to an inner layer by a connecting means and a region where the outer layer is not connected to the inner layer so that a communicating passage having an exit opening to the outer space is formed. On the inside means are provided which connect the interior with the communicating passage. The exit opening is with a Adhesive layer provided that breaks when a certain pressure in the interior of the package breaks.

This ensures a certain overpressure in the package when heated in the microwave, and also ensures controlled release of the overpressure above a certain value.

WO 03/051745 A discloses a package of an unopened, in particular microwaveable material which has at least one sealing region which becomes locally permeable when a specific internal pressure is exceeded, this sealing region having at least one desired passage section forming a throttle for the contents of the package , and which is formed in the form of a channel-like passage, and comprises a packaging interior facing the tip, which is preferably sealed.

Disadvantage of this valve construction is that the valve opens easily not only in the case of overpressure induced by heating, but also under mechanical pressure. Furthermore, the passage is not exactly dimensioned. In addition, there is the possibility that migrated during production, autoclaving, sterilization, storage or heating filling material from the package into the valve, the contents presses the valve then prematurely and can escape into the surrounding space of the microwave oven. But there is also the possibility that the valve is clogged by the infiltrated product ^' and the steam can not escape to the extent necessary. The valve must also be placed in the area of a sealed seam and can not be freely applied in another area of the film.

From WO 04/13015 A a package is known which has an absorber for the escaping moisture during heating, whereby a crisper preparation is possible. Without a valve, through which excess steam can escape, the absorber is used up too quickly. All these packages can not be closed again after opening and can therefore not be stored after opening and removing part of the contents, for example in the refrigerator

The object of the invention was to provide a suitable for heating in the microwave, in the oven or in a water bath packaging in the one hand, the construction of a defined pressure and a controlled escape of steam is possible and makes a steam cooking possible.

The invention therefore relates to a packaging suitable for heating in a microwave oven, in an oven or in a water bath, consisting of a multilayer film material which has at least one region which becomes permeable when an internal pressure generated by the heating is exceeded, characterized in that this region is formed is covered by a micro-perforation covered by a label or hot stamping foil or varnish coating.

The microperforation can be done by needling or by means of a laser beam in the

Foil material are introduced.

The shape of the microperforated area may vary and, for example, the

Shape of a circle, rectangle, square, trapezium, triangle, an elliptical or semi-elliptical shape, but also the shape of defined signs,

Symbols, lines, letters, logos and the like.

The shape of the micro-perforation may be in the form of a circle, a slit, a rectangle, a square and the like.

The arrangement of the circles, slits, rectangles or squares and the like of the micro-perforation may optionally give a logo and the like.

The dimensions of the microperforation in its longitudinal and / or widthwise extent may be 10 μm to 1.5 mm, preferably 50 μm to 1 mm. If appropriate, at least in the microperforated area, a further film can be laminated by means of a varnish or adhesive varnish softenable by the action of heat which has microperforations offset from the first microperforations.

This results in a temporally and spatially offset opening of the microperforated

Valve reached.

The microperforated valve can be applied anywhere on the package.

The microperforated area is covered with an adhesive label, a hot stamping foil and / or a varnish coating.

The paint coating may be aqueous or solid paint systems, in particular also a paint system based on polyester acrylate or epoxy acrylate rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethane, butadiene, styrene or their copolymers which may be conventional or reactive curing (chemical or radiation curing).

Optionally, the lacquer or the microperforation covering label, hot stamping foil or covering lacquer coating may also contain energy absorbing additives such as metallic additives, graphite, energy absorbing pigments or particles and the like. In particular, particles and pigments come into question whose molecular components come into resonance by the incident microwave radiation and are put into thermal oscillation or in which currents are induced by the incident microwave radiation. These are understood in particular to mean pigments or particles which contain molecular water, such as water glass or zeolites. Furthermore, known conductive polymers can also be used.

The paint coating can be prepared by known coating or printing processes, by gravure, flexographic printing, screen printing, offset printing, Digital printing, smooth-roll, raster or line screening method, each with Mitoder counter run, curtain coating and the like are applied to the microperforated area.

When heated in the microwave and the above will be microperforated

Area coating layer, the adhesive layer of the label or the

Hot embossing film brittle and thus permeable, the resulting steam can escape.

When the packaging cools, the microperforation is closed again by the cooling paint.

Furthermore, the microperforation can be closed again by mechanical pressure, for example by re-pressing the adhesive label.

In this case, the label may be provided with an adhesive coating that adheres firmly in a defined area outside the micro-perforation even when heated, but in the field of micro-perforation is replaced when heated. Upon cooling, this adhesive coating is again klebefähig and that

Label can be reconnected to the foil by mechanical pressure.

As a result, the packaging can be sealed again and, for example, stored until further use, optionally with cooling.

The film material of the packaging is two or more layers. The outer layer preferably consists of a film of plastic, for example polyester, such as oriented PET amorphous PET, polyolefins such as polypropylene, cast-PP, blown, stretched, biaxially oriented PP films, or polyethylene, polystyrene, polycarbonate, cellophane, polyamide, polyvinyl chloride or their copolymers. However, coextruded or laminated plastic composite films or composites with paper can be used. Further, it is possible to use coated films, biodegradable films, aluminum foils and the like. The thickness of the outer layer is preferably 8-200 μm. The inner layer preferably consists of a sealable medium, for example of plastic films of polyolefins, such as polyethylene, polypropylene, of EVOH ₁ EVA, and / or its copolymers or terpolymers, polystyrene, polycarbonate, cellophane, polyamide, polyvinyl chloride. The inner layer can also be formed by extrusion coating or painting the outer film with one of the plastics mentioned. The thickness of the inner layer is preferably 0.5-100 μm.

Intermediate layers may optionally be located between the outer and inner layers. Such intermediate layers can be, for example, barrier layers, such as aluminum oxide layers or silicon oxide layers, organic barrier layers, such as polyamide layers, absorber layers, for example gas absorber layers, such as O ₂ , CO ₂ absorber layers, water vapor absorber layers,

Ethylene-absorber layers, printed layers, layers imparting increased flexibility or strength or rigidity, and the like. The entire layer composite of the packaging according to the invention may optionally comprise a plurality of intermediate layers and combinations of these intermediate layers, wherein the layers either each have good adhesion to each other or may be interconnected by adhesive aids such as adhesives.

In order to detect the opening of the micro-perforated valve, a feature can be applied around this area on the film material and the covering material in each case, such that when it becomes permeable, it shows a clear change in the appearance.

In this case, for example, two different colored features can be applied, which form a mixed color in the covered state. After opening the valve, the two layers are separated, the pure colors appear. Furthermore, provision can be made for proving the opening of the valve to apply partial information to the separating layers, which then, after opening, supplement themselves with understandable information, for example lettering, for example "open" or "open" and the like. This can be done using auxiliary layers with different adhesive strength.

Furthermore, on the side of the inner layer facing the interior of the packaging, one or more absorber layers can be provided for the water vapor formed during the heating. As such absorber layers, for example, hydrophilic polymers, such as EVA, highly filled with zeolites polymers, silica gel, nonwovens, or tissue have embedded the hydrophilic polymers, zeolite-coated nonwovens or tissue in question.

In one embodiment, the absorber layer may be applied to the inner layer by printing processes.

However, the absorber layer can also be fixed to the inner layer with a thin sealing layer or membrane. The fixation layer or the membrane may have a predetermined breaking point. When a defined pressure in the package is exceeded, the membrane is stretched and ruptures at the predetermined breaking point, whereby the absorber layer is exposed and the resulting water vapor can be absorbed.

Instead of the absorber layer may under such evt. Additional

Membrane also flavorings, such as incense, or the like may be present, which then at a defined pressure is exceeded

Opening the membrane to be released.

In order to produce a characteristic aroma, encapsulated aroma substances can also be introduced in the valve region, which are released when the valve is opened. Furthermore, the packaging may have a preferably recloseable opening aid, for example a laser perforation, a tear-open thread, wherein this opening can then be resealed by applying a label.

When introducing a laser perforation, both the microperforation of the valve and the opening aid can be introduced by modulation of the laser energy in a single operation.

As an opening aid but also zipper or sliding closure-like devices come into question, which are self-resealable.

The packaging may be in the form of a bag, a bag, a stand-up pouch, a tray, sachet, pouch or in the form of a sealing film for containers.

Claims

claims:

1) For heating in a microwave oven, in the oven or in a water bath suitable packaging consisting of a multilayer film material having at least one area which becomes permeable when an internal pressure generated by the microwave heating is exceeded, characterized in that this area is formed by a micro perforation which is covered by a label or a hot stamping foil or by a lacquer coating.

2) Packaging according to claim 1, characterized in that the microperforated area, for example, the shape of a circle, rectangle, square, trapezium, triangle, an elliptical or semi-elliptical shape, but also the shape of defined characters, symbols, letters, logos and the like ,

3) Packaging according to one of claims 1 or 2, characterized in that the micro-perforation in the form of a circle, a slot, a rectangle, a square and the like is executed.

4) Packaging according to one of claims 1 to 3, characterized in that the microperforation results in the shape of a logo.

5) Packaging according to one of claims 1 or 2, characterized in that the microperforated area by a paint coating based on a mixture or a polyester acrylate or epoxy acrylate rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate -, urethane systems, butadiene, styrene or their copolymers. 6) Packaging according to claim 3, characterized in that the lacquer coating, the label or the hot stamping foil contains an energy-absorbing additive.

7) Packaging according to one of claims 1 to 4, characterized in that intermediate layers are provided between the outer and inner layer.

8) Packaging according to claim 5, characterized in that the intermediate layers, barrier layers, absorber layers, browning layers, flexibility or strength or rigidity and / or printed layers.

9) Packaging according to one of claims 1 to 6, characterized in that on the interior of the packaging facing side of the inner layer, an absorber layer is present, which is fixed by a membrane having a predetermined breaking point.

10) Packaging according to one of claims 1 to 7, characterized in that different features are applied in the region of the microperforation, which show a significant change in the visual appearance after opening the valve.

11) film material for the production of packaging according to one of claims 1 to 8.