WO2007036302A1

WO2007036302A1 - Packaging container with a high degree of gas impermeability and method for producing it

Info

Publication number: WO2007036302A1
Application number: PCT/EP2006/008942
Authority: WO
Inventors: Andreas Rothschink
Original assignee: Abro Weidenhammer Gmbh
Priority date: 2005-09-23
Filing date: 2006-09-14
Publication date: 2007-04-05
Also published as: DE102005045621A1

Abstract

A method of producing a packaging container, such as a carton for receiving food, is proposed, the packaging container having a base and a body of a plasticizable polymer material. In this method, the polymer material is plasticized and moulded to form the packaging container by injection moulding. Before the plasticized polymer material is injected into a suitable mould, at least one film is arranged in the mould and the plasticized polymer material is injected around the film in the manner of in-mould labelling. In order to obtain a high gas barrier of the packaging container in a simple and inexpensive way, it is provided according to the invention that the at least one film is arranged in the mould in such a way that the polymer material is injected around it essentially over the entire area made up by the base and the body, and that a film which has a higher degree of gas impermeability than the polymer material of the packaging container in the solid state is used. The invention also relates to a packaging container of the aforementioned type.

Description

Packaging container with high gas-tightness and process for its preparation

The invention relates to a method for producing a packaging container, such as a cup, in particular for holding food, having a bottom and a casing made of a plasticizable plastic material by the plastic material is plasticized and molded by injection molding to the packaging container, wherein before injecting the plastifzierten plastic material disposed in a suitable mold at least one film in the mold and the film is back-injected in the manner of in-mold labeling with the plasticized plastic material. The invention is further directed to a packaging container, in particular produced according to such a method, such as a cup, in particular for holding food, with a bottom and a shell of a plasticizable plastic material, wherein on the outside of the packaging container at least one film is applied such that it is at least partially fused with the plastic material of the packaging container.

Packaging containers of this kind enjoy great popularity, in particular for storing liquid, pasty or solid foods and beverages, such as yoghurts, quark foods, creams, ce- reales, biscuits, fresh or granulated pet food, coffee, tobacco and the like. You find For example, in the form of substantially cylindrical or conical cups made of plastic materials, mainly in the form of polypropylene (PP), but also polyethylene (PE), polyalkylene terephthalates and the like, various uses. Of particular advantage is their low price while ensuring a high level of hygiene, the low price of such packaging container or cup results from the fact that they are inexpensive to produce by injection molding. Consequently, on the one hand a cost-effective mass production is possible, on the other hand, with a required wall thickness of such packaging containers of usually about 400 microns to 500 microns only a relatively small amount of plastic material per packaging container needed.

A serious disadvantage of such packaging containers, however, is that they are not entirely diffusion-tight, resulting in perishable contents, such as food, to a shortening of the generally possible shelf life. It should be noted that food is usually bottled under vacuum and / or under inert gas atmosphere in such packaging containers, but due to the insufficient tightness of the container with time water vapor and in particular oxygen penetrates through the plastic material of the container inside and there chemically in particular can react biochemically with the contents.

Although highly diffusion-tight packaging containers made of plastic are known, which are multi-layered and arranged between two outer layers of a thermoplastic material, such as polypropylene, arranged barrier layer of a thermoplastic material, such as ethylene vinyl alcohol (EVOH). Such containers are used, for example, for ready meals. tion, wherein the container itself has a plurality of recesses for receiving various foods, for example, on the one hand meat, on the other vegetables and / or pasta, and is closed at its open top of a peelable film. However, the production of such packaging container is relatively complicated and expensive, since the multilayer plastic composite must first be extruded and then the same must be thermoformed to the shape of the packaging container, in particular to form the recordings thereof. In the conventional use of EVOH as Barrie- rer layer is added that this plastic is extremely hygroscopic, with its tightness with increasing absorption of water (steam) decreases sharply, which is a further disadvantage especially in a sterilization, for example using autoclave , This phenomenon is also referred to as "retort shock" by EVOH. After delivery of the water (steam) over several days or weeks EVOH regains its good barrier properties, which is why more barrier materials, such as metal particles, are often used, which initially, as long as the EVOH after sterilization of the packaging container still no sufficient gas barrier can form, bind penetrating atmospheric oxygen. As readily apparent, such a measure makes the known packaging container more expensive.

The invention has the object of developing a generic packaging container and a generic method for producing the same to the effect that with a simple and inexpensive production by injection high gas tightness and a low diffusion coefficient, especially against atmospheric oxygen and humidity, is ensured. In procedural terms, this object is achieved in a method of the type mentioned in that the at least one film is arranged in the mold so that it is back-injected substantially on the entire bottom and shell side with the plastic material, and that a film used is, which has a relation to the plastic material of the packaging container in the solid state higher gas tightness.

In terms of product technology, the invention further provides for a packaging container of the type mentioned above, that the at least one film is applied substantially to the entire bottom and shell side of the packaging container, and that the film has a relation to the plastic material of the packaging container higher gas-tightness.

The invention makes it possible in a very simple and cost-effective manner to provide a generic packaging container, such as a cup, with excellent gas-tightness, by covering both its bottom surface and its surface over its entire surface with a film having high barrier properties in the manner of itself known in MoId labeling (IML) is applied. In this way, the packaging container can continue to produce inexpensively by injection molding and can be plastic material in particular from the conventionally provided for this purpose polymers, such as polypropylene, polyethylene, polyethylene terephthalate and the like, be formed without a higher wall thickness of the container would be required. Furthermore, no additional process steps are required for lending the high diffusion barrier according to the invention since, as a rule, at least one label-for example, identifying the content and / or the manufacturer-is applied to the packaging container, which is also possible. Currently often done by the IML process by inserting a film in the injection mold and the film is back-injected with the molten plastic material by taking an intimate fusion. According to the invention, only the film (s) will now be selected so as to have a significantly higher gas tightness relative to the plastic material of the container, and the films are applied over the entire surface of the container, in addition to the desired gas tightness and thus a longer shelf life of the container contents to care. It can, of course, as desired, as well as previously provided for labels foils at least partially be provided with imprints, dyeings, pigmentations, etc.

Depending on the film used or depending on the nature of the barrier layer (s) of the same, it is easily possible to give the packaging container by more than a hundred times higher gas tightness than in a conventional - as such identical - packaging container, but without film coating or with a only partial film coating using conventional films without barrier properties is the case. An advantageous embodiment therefore provides that a film is used whose gas-tightness is at least about 10 times higher, in particular at least about 20 times higher, preferably at least about 50 times higher and most preferably at least about 100 times higher than the gas-tightness of the plastic material in solid (ie solidified) state. As explained in more detail below with reference to specific exemplary embodiments of films that can be used according to the invention, a gas-tightness of the packaging container that is increased by more than about a thousand times can be achieved without difficulty over a packaging container that is not coated with such a film over the entire surface. By "back-injected" within the meaning of the invention, by the way, it is merely meant that the plasticized plastic material of the packaging container is sprayed onto at least one side of the film according to the in-mold labeling method. The film can be back-injected as desired on the inside or outside of the packaging container or on both sides with the plasticized plastic material. By "film" within the meaning of the invention, an at least single-layer ("monofilm") or multilayer film is addressed, which takes into account the desired tightness values of the container.

In a preferred embodiment, it is provided that a film is used, which has an oxygen permeability rate of at most about 50 cm ³ / m ² 'd ^* bar, in particular of at most about 10 cm ³ / m ² ' d 'bar, preferably of at most about 5 cm ³ / m ² "d" bar and most preferably of at most about 1 cm ³ / m ^{2 *} d ^* bar. As also explained in more detail below, also oxygen permeability rates of about 0.1 cm ³ / m ² "d" bar or less possible, ie by an area of the film used for the packaging container according to the invention of 1 m ² diffused per day 1 bar pressure an oxygen volume of 0.1 cm ³ or less. For comparison, for example, polypropylene as the common plastic material of the packaging container has an oxygen permeability rate of about 3,000 cm ³ / m ^{2 *} d "bar to about 4,000 cm ³ / m ^{2 *} d 'bar.

In a further preferred embodiment, it is provided that a film is used, which has a water vapor transmission rate of at most about 50 g / m ^{2 *} d, in particular of at most about 10 g / m ² "d, preferably of at most about 5 g / m ² "d, and most preferably at most about 1 g / m ² " d. As also explained in more detail below, also water vapor transmission rates of about 0.1 g / m ^{2 •} d or less are possible, ie by a surface of the film used for the packaging container according to the invention of 1 m ² per day diffused water vapor amount of 0.1 g or less.

In an expedient embodiment, a multilayer film is used, which has at least one outer-side cover layer, an inner-side adhesion-promoting layer and a barrier layer arranged between them. In this case, the adhesion-promoting layer provides an intimate fusion bond with the plastic material of the actual packaging container and can be formed from the same or a plastic material compatible with the plastic material of the packaging container, for example polypropylene (PP), eg oriented polypropylene (oPP), polyethylene (PE ), Polyethylene terephthalate (PET), thermoplastic paints (TP paints) or the like. The melting range of this primer layer may preferably be higher than that of the plastic material of the container, with which the film is back-injected, so that it is not fully plasticized. This is also possible in the case of an adhesion-promoting layer of the same material as that of the container, for example, by adding the adhesion-promoting layer with suitable additives and / or the respective polymer of the adhesion-promoting layer having longer and / or branched polymer chains. The outer-side cover layer, which can also be formed, for example, from a polymer such as PP, PET, polyamide (PA), etc., from a lacquer or the like, serves to protect the barrier layer. It can also - provided that applied by in-mold labeling film with imprints is to provide optical effects, such as gloss, as known in conventional IML labels with proper finish. Of course, the multilayer film of the packaging container with at least one outer side cover layer, an inside adhesion promoting layer and a barrier layer arranged therebetween further layers, such as additional barrier layers, adhesive or bonding layers applied between individual layers, decorative, eg printed, layers etc .. . exhibit.

According to a preferred embodiment it can be provided that a film is used whose barrier layer comprises at least one metal or metal oxide, in particular from the group of silicon oxide, aluminum oxide and aluminum. Such a barrier layer, for example, by physical vapor deposition (PVD), chemical vapor deposition (chemical vapor deposition, CVD), sputtering, metallizing, etc. directly on the outside cover layer, the inside

Adhesive layer and / or applied to other adhesive or primer layers. In particular, silicon dioxide (SiO _x ) has the additional advantage that it is not only highly gas-tight, but also easily printable in order to simultaneously serve as a carrier matrix of an imprint. Basically, such barrier layers of metal (oxide) can achieve perfect gas tightness even at a layer thickness of only a few atomic layers, ie in a range from about 1 nm to about 100 nm. Another advantage of such metallic barrier layers, such as SiO _x , is that. they are perfectly sterilizable and have no so-called retort shock, as for example - as mentioned above - is the case with EVOH. Alternatively or additionally, it can be provided according to a further preferred embodiment that a film is used whose barrier layer comprises at least one polymer from the group ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide (PA) and blends thereof. Such a barrier layer can be laminated, for example, to the outer-side cover layer, the inner-side adhesion-promoting layer and / or further adhesive or adhesion-promoting layers, or applied in the form of a lacquer.

The film should preferably have a total thickness of between about 30 microns and about 150 microns, in particular between about 50 microns and about 100 microns, on the one hand for a sufficient rigidity when inserted into the mold or when injecting the film with the plasticized plastic material of the packaging container so that the film does not collapse or slip in the mold. On the other hand, the film should not be too stiff for processing reasons and should not exceed a certain thickness for optical reasons. Of course, the film may also be significantly thinner, e.g. have a thickness of standard films of about 10 μm to 12 μm, provided that they have the required barrier properties and are sufficiently easy to handle in in-mold labeling (for example by sucking the film onto the molding space of the molding tool or the like)

In many cases it may be desirable to use a substantially transparent film. In a packaging container which is fully coated with a substantially transparent film, the color of the plastic material as well as one in most Falls desired printing through the film or through at least one (outer) layer of the film visible.

The packaging container according to the invention is expediently closed on its open, side facing away from the bottom after filling, in particular by sealing a sealing membrane. Alternatively or additionally, a cover, such as a screw or slip lid or even such may be provided in the form of a tamper-evident closure in order to protect such a membrane from mechanical damage from the outside or even to provide the required tightness. In the latter case, the lid may e.g. in turn be provided with a barrier layer.

The invention is explained in more detail with reference to an embodiment.

embodiment

A packaging container in the form of a cup made of polypropylene with a wall thickness of 450 μm is produced by injection molding by plasticizing the polypropylene and injecting it by means of an injection molding machine into a suitable mold. In order to ensure a high gas-tightness of the packaging container, both the bottom and the outer surface of the cup completely covering films are arranged in the Formwerk- and these injected behind the type of in-mold labeling (IML) with the plasticized polypropylene. IML films are used according to the following structure (viewed from outside to inside each): a) Slide 1:

- Topcoat (PET), about 5 to 20 microns;

- barrier layer (SiO _x , printed), about 10 to 1000 nm;

- adhesive layer, about 1 to 5 microns;

- Bonding layer (PP), about 50 microns.

b) film 2:

- Covering layer (PET), approx. 30 to 70 μm; - barrier layer (SiO _x , printed), about 10 to 1000 nm;

- Bonding layer in the form of TP paint (PP), about 15 to 20 microns.

c) film 3: - topcoat (paint), about 1 to 5 microns;

- Interlayer (PP), about 5 to 20 microns;

- adhesive layer, about 1 to 5 microns;

- barrier layer (SiO _x ), about 10 to 1000 nm;

- Bonding layer (PP), about 20 to 50 microns.

d) foil 4:

- Topcoat (PET), about 5 to 20 microns;

- barrier layer (Al, metallized), about 10 to 1000 nm;

- adhesive layer, about 1 to 5 microns; - Bonding layer (PP), about 50 microns.

e) Slide 5:

- Cover layer (PP), about 5 to 50 microns;

- barrier layer (EVOH), approx. 5 to 20 μm; - Bonding layer (PP), about 5 to 50 microns.

The packaging containers coated over the entire surface with the above-mentioned films have oxygen transmission rates or water vapor transmission rates, which in all cases are less than 10 cmVm ² 'd' bar and 10 g / m ^{2 *} d, respectively. An uncoated, otherwise identical cup of the same polypropylene with a wall thickness of 450 microns, in contrast, has an oxygen transmission rate of about 3,200 cm ³ / m ² 'd' bar. The example thus shows that the invention enables in a simple and cost-effective manner an extremely effective increase in the gas-tightness of a generic packaging container by a factor of several orders of magnitude.

Claims

claims

A method for producing a packaging container, such as a cup, in particular for holding food, having a bottom and a shell made of a plasticizable plastic material by the plastic material is plasticized and molded by injection molding to the packaging container, wherein prior to injecting the plasticized plastic material in a suitable mold at least one film is arranged in the mold and the film is back-injected in the manner of in-MoId labeling with the plasticized plastic material, characterized in that the at least one film is arranged in the mold so that they are substantially on the entire bottom - And shell side is back-injected with the plastic material, and that a film is used which has a relation to the plastic material of the packaging container in the solid state higher gas tightness.

2. The method according to claim 1, characterized in that a film is used, the gas-tightness of which is at least 10 times higher, in particular at least 20 times higher than the gas-tightness of the plastic material in the solid state.

3. The method according to claim 1 or 2, characterized in that a film is used whose Gasdichtig- speed is at least 50 times higher, in particular at least 100 times higher than the gas-tightness of the plastic material in the solid state.

4. The method according to any one of claims 1 to 3, character- ized in that a film is used, which has an oxygen transmission rate of at most 50 crnVrn ^{2 *} d 'bar, in particular of at most 10 cm ³ / m ^{2 •} d ^* bar ,

5. The method according to any one of claims 1 to 4, characterized in that a film is used, which has an oxygen permeability rate of at most 5 cm ³ / m ² 'd "bar, in particular of at most 1 cm ³ / m ^{2 *} d" bar, having.

6. The method according to any one of claims 1 to 5, characterized in that a film is used, which has a water vapor transmission rate of at most

50 g / m ² 'd, in particular of at most 10 g / m ² ' d.

7. The method according to any one of claims 1 to 6, characterized in that a film is used, which has a water vapor transmission rate of at most 5 g / m ² "d, in particular of at most 1 g / m ^{2 *} d.

8. The method according to any one of claims 1 to 7, characterized in that a multilayer film used is, which has at least one outer-side cover layer, an inner side primer layer and a barrier layer arranged between them.

9. The method according to any one of claims 1 to 8, characterized in that a film is used, the barrier layer comprises at least one metal or metal oxide, in particular from the group of silica, alumina and aluminum.

10. The method according to any one of claims 1 to 9, characterized in that a film is used whose barrier layer at least one polymer from the group ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide (PA) and blends thereof having.

11. The method according to any one of claims 1 to 10, characterized in that a film having a total thickness between 30 .mu.m and 150 .mu.m, in particular between 50 .mu.m and 100 .mu.m, is used.

12. The method according to any one of claims 1 to 11, characterized in that a substantially transparent film is used.

13. The method according to any one of claims 1 to 12, characterized in that the packaging container at its end facing away from the bottom, open side after filling, in particular by sealing a sealing membrane, is closed.

14. Packaging containers, such as cups, in particular for holding foods, having a base and a casing made of a plasticizable plastic material, where in that at least one film is applied to the outside of the packaging container in such a way that it is at least partially fused with the plastic material of the packaging container, in particular according to a method according to one of claims 1 to 13, characterized in that the at least one film substantially is applied to the entire bottom and jacket side of the packaging container, and that the film has a relation to the plastic material of the packaging container higher gas tightness.

15. Packaging container according to claim 14, characterized in that the gas-tightness of the film at least 10 times higher, in particular at least 20 times higher than the gas-tightness of the plastic material in the solid state.

16. Packaging container according to claim 14 or 15, characterized in that the gas-tightness of the film at least 50 times higher, in particular at least 100 times higher than the gas-tightness of the plastic material in the solid state.

17. Packaging container according to one of claims 14 to 16, characterized in that the Sauerstoffdurchlässig- keitsrate the film is at most 50 cm ³ / m ^{2 *} d "bar, in particular at most 10 cm ³ / m ² 'd' bar, is.

18. Packaging container according to one of claims 14 to 17, characterized in that the Sauerstoffdurchlässig- keitsrate the film is at most 5 cm ³ / m ² 'd ^* bar, in particular at most 1 cm ³ / m ^{2 *} d ^* bar.

19. Packaging container according to one of claims 14 to 18, characterized in that the Wasserdampfdurchlässig- keitsrate of the film is at most 50 g / m ^{2 *} d, in particular at most 10 g / m ^{2 *} d.

20. Packaging container according to one of claims 14 to 19, characterized in that the Wasserdampfdurchlässig- keitsrate the film is at most 5 g / m ² 'd, in particular at most 1 g / m ^{2 •} d.

21. Packaging container according to one of claims 14 to 20, characterized in that the film is formed in multiple layers and at least one outer side cover layer, an inner side primer layer and a zwi arranged this arranged barrier layer.

22. Packaging container according to one of claims 14 to 21, characterized in that the film has a barrier layer with at least one metal or metal oxide, in particular from the group of silica, alumina and aluminum.

23. Packaging container according to one of claims 14 to 22, characterized in that the film has a barrier layer with at least one polymer from the group

Ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide (PA) and blends thereof.

24. Packaging container according to one of claims 14 to 23, characterized in that the film has a total thickness between 30 .mu.m and 150 .mu.m, in particular between 50 .mu.m and 100 .mu.m.

25. Packaging container according to one of claims 14 to 24, characterized in that the film is substantially transparent.

26. Packaging container according to one of claims 14 to 25, characterized in that it is closed on its side facing away from the bottom, open side, in particular of a sealing membrane.

27. Packaging container according to one of claims 14 to 26, characterized in that it is closed on a side facing away from the bottom of a lid.