EP0243430A1

EP0243430A1 - Composite foil for packing purposes

Info

Publication number: EP0243430A1
Application number: EP86906330A
Authority: EP
Inventors: Horst Biermann
Original assignee: IMDUT INTERNATIONAL BV
Current assignee: IMDUT INTERNATIONAL BV
Priority date: 1985-10-25
Filing date: 1986-10-27
Publication date: 1987-11-04
Also published as: DK323387A; AU606041B2; NL193058C; NL8502931A; NL193058B; AU6593686A; DE8690142U1; DK323387D0; WO1987002647A1; JPS63501556A

Abstract

Les sacs tubulaires sous vide, par exemple pour denrées alimentaires sous forme de poudre, sont généralement emballés dans une feuille d'aluminium et un nouvel emballage est ensuite absolument nécessaire en raison de l'aspect plissé de ce genre d'emballage. Une nouvelle feuille composite est caractérisée par le fait que deux couches posées l'une contre l'autre sont reliées mutuellement par adhésion, mais cette liaison peut cependant être rompue immédiatement. Cette condition peut être réalisée dès que le sac a été évacué de la manière habituelle, le sac intérieur se retrécit autour de la marchandise et pendant cette opération le sac extérieur se détache par la suppression de l'adhésion qui jusqu'alors a été maintenue; ensuite les couches ci-dessus décrites sont séparées. Le résultat obtenu est un sac extérieur plutôt lisse, alors que le sac intérieur plissé, qui est invisible, reste enfermé à l'intérieur du sac extérieur. Ce dernier peut donc être utilisé comme nouvel emballage surtout dans les cas où les feuilles composites ne peuvent en aucune manière être distinguées d'un sac habituel avant son utilisation comme sac d'emballage lorsqu'il est mis sous vide.Tubular vacuum bags, for example for foodstuffs in powder form, are generally wrapped in aluminum foil and new packaging is then absolutely necessary because of the pleated appearance of this kind of packaging. A new composite sheet is characterized in that two layers placed one against the other are connected to each other by adhesion, but this connection can however be broken immediately. This condition can be achieved as soon as the bag has been evacuated in the usual manner, the inner bag shrinks around the goods and during this operation the outer bag is detached by the removal of the adhesion which until then has been maintained; then the layers described above are separated. The result is a rather smooth outer bag, while the pleated inner bag, which is invisible, remains enclosed inside the outer bag. The latter can therefore be used as new packaging, especially in cases where the composite sheets cannot in any way be distinguished from a usual bag before its use as a packaging bag when it is placed under vacuum.

Description

MULTIPLE COMPOSITE FILM FOR PACKAGING PURPOSES

Multiple composite film for packaging purposes, in particular for vacuum packaging purposes and method for their use as packaging bags.

The present invention relates to a multi-layer film for special use in packaging of e.g. Food in powder form with simultaneous application of an evacuation process with or without addition of support gas. Laminated packaging films have long been known for the stated purposes and, as is known, evacuated packaging bags are not nice to look at, which is why a repacking is always required so that the product has a good appearance for sale. The repackaging also serves to prevent possible perforation of the evacuated pouch as far as possible and precisely where such perforation can easily occur, i.e. in places where there are sharp-edged bumps. The sensitivity of an evacuated packaging to undesired perforation is all the greater since the granular, powdery particles are sharp-edged. But the perforation can also start on the outside.

The invention intends to create a novel multiple composite film which, as is well known, strives to assign all the necessary properties to a film, which result in opaque values, light tightness values and strength values being optimal and at the same time being price-acceptable, but additionally the novel composite film is increased a surprising feature that has never been found before.

According to the invention, a gas-impermeable multiple-composite film for packaging purposes is particularly suitable for packaging oxygen-sensitive or oxygen-reacting foods and the like with negative pressure, the inner layer representing an independent gas-impermeable vacuum packaging within a gas-impermeable, light-tight and mechanically highly resilient independent outer packaging, characterized in that more ¬ re layers of thermoplastic film material and a layer or layer of substrate material, which are arranged in a superimposed relationship and laminated together, as well as a layer of thermoplastic films ¬ material which is arranged in a related relationship, wob ei ei ne non-permanent Ver dependent on later application of force on the composite film Bond between the layers. During the production process of the multi-layer film is in particular only effected by using adhesion or by using adhesion promoter.

The invention also relates to a bag which is produced from a composite film according to the invention and which looks attractive on the outside, but which is known to be shrunk on the inside in the case of vacuum packaging and which looks attractive when the outside of the bag is torn or opened. In addition, the specifics are To determine the properties of the separate layers of the composite film in such a way that an optimal strength of the

Outer layer in connection with an optimal strength of the inner layer of the bag ensure that an undesired perforation does not even occur and even if it would occur, at most only the "outer bag" will perforate, but not at the same time the "inner bag" so that an extremely effective storage the inner bag, especially the evacuated one

Inner ice is guaranteed.

This new multi-layer film is particularly suitable for packaging milk in powder form to replace expensive conventional cylindrical tin packaging cans. In addition, the intended bag packaging now enables space-saving, evacuated block packaging to be produced, namely small packaging, e.g. of 200 gr. but also large packaging, e.g. from 250 to 2,000 kg. Multiple composite films according to the invention have already been subjected to tests, with small bags being run over by a truck without there being any cause for (known) perforations!

The packaging bag according to the invention makes the usual use of a so-called repacking unnecessary. It is now possible according to the invention that the otherwise customary, shrinkable, evacuated inner packaging is provided by the smooth, attractive outer bag, which is normally followed by the desired one

Printing is already attached.

It has been shown that this new packaging is particularly suitable for storing milk powder that can be evacuated in the bag using the packaging. Usually milk powder is put in tin cans stored low vacuum and this milk powder has only a limited use-up time. When using the new, highly gas-impermeable and highly tough multiple-composite film, it is now possible to store milk powder guaranteed for at least 2 years without any quality deterioration being felt. This guarantee is basically also given for milk powder if the product is stored outside of freezer rooms in tropical countries.

The invention also intends a method whereby two layers which are placed opposite one another can be separated from one another using the special properties of the multiple composite film according to the invention. In particular, a shrink-looking evacuated inner bag then separates from a smooth-looking outer bag. The last one can thus be provided with a legible advertising imprint that is otherwise never directly applicable to vacuum packaging.

The invention is shown purely schematically in the drawing using two exemplary embodiments of a multiple composite film. . ^"Figure 1 shows a first inventive five layer lie Verpackungsverbundfo-;

2 shows a second six-layer packaging composite film, both in an exploded view.

The multilayer, highly tough and gas-impermeable vacuum packaging material in the figures contains a first outer layer, or film 1, and made of a thermoplastic material, which is arranged on the opposite side of an inner layer, or film 2. This layer can consist of a monoaxial or biaxial film made of polyamide (nylon) or of another suitable material. Layer 3 is firmly connected with a suitable material, for example aluminum foil. The next layer 4 can again consist of a monoaxial or biaxial film made of polyamide (nylon) or of another suitable material. The last composite layer 5 can consist of an aligned coextruded polyethylene and / or a copolymer and / or an olefin or and / or an extrudable ionomer from several layers. All layers 1-5 are laminated together and form the outer composite. An inner layer 6 of an aligned coextruded polymer of lower density and / or a copolymer and / or an olefin or and / or an extrudable ionomer from several layers or layers is applied to this composite by means of adhesion. This creates a loose one

Compound, between the outer layer 1 -5 and the inner layer 6, but which is firm enough to ensure processing from the roll on a conventional tubular bag forming and filling machine.

On Grunti of the metal film 3 and the composition of layer 5, the outer composite combination alone has an extremely significant gas barrier property, such that this part of the packaging material has a permeability rate to oxygen or another gas in the order of magnitude of 0.3 or less has, the rate in cm3 _/ 2 - i r -.- _ι ■ • _ _.

'- ^y ' / m per mil thickness over a period of 24 hours at atmospheric normal pressure and room temperature of approx. 24 ° C at 50% relative humidity. The inner layer or layer has a similar gas barrier property such that this part of the packaging material has a permeability rate to oxygen or another gas in the order of magnitude of 0.5 or less.

The materials for the outer layer 1-5 were selected from the point of view that the packaging laminate has to ensure strength, flexibility and excellent gas impermeability in the event of damage to the inner packaging, layer 6, which in turn exhibits excellent gas impermeability and, in the event of partial damage from the outside inwards, still provides full product protection, or the entire packaging retains its shape formed under vacuum and thus remains usable.

The inner layers 5 and 6 can be used in any thickness, however the preferred thickness range for the small packages for these two layers 5 and 6 is approximately 0.0300 to 0.0400 mm, with approximately 0.0352 to 0.0375 mm in generally to achieve the desired properties of the Small packaging are preferred.

This multilayer packaging material can be processed in the usual way to form containers or packaging, preferably those which can be vacuumed, with or without addition of support gas, but can be sealed airtight.

For example, the packaging material can be used to produce stable bags or sacks with a conventional tubular bag forming and filling machine with an open end, which after the contents have been introduced, e.g. Milk powder, vacuumed in a vacuum device, back-gassed if necessary, and can be sealed by heat. Here, the inner layer 6 takes over the entire atmospheric pressure since there is pressure equalization between the two layers 5 and 6 loosely connected by means of adhesion. After the pressure has been equalized, layers 1 to 5 are finally sealed with layer 6. As a result of this process, the packaging (inner bag) is created in the packaging (outer bag), with both packaging being extremely impermeable to gas and a further outer packaging in a paper wrap or a carton is not necessary.

The outer layers of thermoplastic film material, which extends the inner layer of substrate material (aluminum foil), are thus laminated tightly with one another, while the inner layer is not laminated to the outer composite, but is only bonded by means of adhesion, so that one deliberate detachment from the carrier film can take place after vacuuming.

With regard to the application of the method with which this adhesion can subsequently be canceled using the intended adhesion, or the inner bag can be separated from the outer bag as soon as pressure and tension differences occur, little need be explained further. The specialist has long been familiar with evacuation processes for tubular bags, so that there is no need to discuss them here. The "inner" separation according to the invention speaks for itself; the "adhesion" mentioned can have many possibilities and is therefore not in its class

Design limited. Therefore, adhesion promoters of any suitable type can be applied if they are only useful.

Claims:

Claims

PATENT CLAIMS

1. Gas-impermeable multiple composite film for packaging purposes, particularly suitable for packaging oxygen-sensitive or oxygen-reactive foods and the like with negative pressure, the inner layer being an independent gas-impermeable vacuum packaging within a gas-free

05. permeable, light-tight and mechanically highly resilient independent outer packaging, characterized in that several layers of thermoplastic film material and a layer or layer of substrate material, which are arranged in a superimposed relationship and laminated together, and a layer of thermoplastic film material this in

1 0 superimposed relationship is arranged, wherein a non-permanent connection between the layers during the manufacturing process of the multiple composite film is achieved in particular only by adhesion or by the use of adhesion promoters.

1 5.

2. Multiple composite film for packaging purposes according to claim 1, characterized in that when the composite film is used as the packaging bag, the inside of the packaging film (inner bag) largely adjoins the unevenness of the goods to be packaged under the prevailing negative pressure, while the outside of the packaging film (outer bag) at or

9 - n ^u after packaging partially detaches from the inner part of the packaging film in such a way that the unevenness on the inside does not occur on the inside

Be visible on the outside of the multiple composite film.

3. Bag made of a multiple composite film according to one of the preceding ^ 5 claims 1-2, characterized in that initially and as long as

Packaging is not subjected to negative pressure, the inner bag is integrally connected to the outer bag and this connection can only be released locally after an application of force due to pressure differences between the inner and

Outer bag occurs. 30

4. Bag according to claim 3, characterized in that the inner bag shrinkingly comprises its contents under the prevailing negative pressure and the outer bag envelops the inner bag in usually smooth and attractive manner as visible packaging.

5. A method for producing a multiple composite film according to one of the preceding claims 1-2 for use in packaging according to claims 3-4, characterized in that by means of a non-permanent adhesion initially intended between two layers of film stacked one on top of the other

D5 adhesion is normally pre-formed in the composite film, but the type of adhesion that occurs is such that afterwards, with pressure equalization occurring, in particular internal pressure equalization, between the layers in question when used in pressure packaging, the initially manifesting adhesion between the two superimposed layers

10 can be canceled and thus these layers can then be separated from each other relatively easily.

6. Method for closing a tubular packaging bag while simultaneously using a multiple composite film according to one of the previously

1-5 claims, characterized in that the outer part of the packaging bag (the overpack), after the inner part thereof is exposed to the packaging pressure (vacuum), gradually separates therefrom, so that the outer bag which is then formed is relatively smooth and attractive looks in such a way that it can be used as an overpack with pre-printed advertising

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