LAYERED PACKAGE WITH A SEAM

The present invention is directed to a package with at least one seam having at least at one side a humidity-, liquid- and/or fat-tight surface layer on a substrate layer.

Many such packages are well known according to the relevant state of the art. With all such packages problems occur, when a seam is formed, especially if renewable materials like PLA are used for impregnation, coating or the like of a base material.

Often such seams are weak and not tight.

The aim of the present invention is to find a solution for the disadvantages of such known packages.

In the solution of these problems proposed by the present invention, a primer is arranged in the area of the seam at least on one side of the packaging and/or between the substrate layer and the surface layer.

With such a primer a strong and tight seam can be formed. Further the surface layer can be easily bonded to to the substrate layer. According to another embodiment it is very advantageous if the surface layer is made from a accordingly equipped paper or a plastic material, e.g. EVOH, PVOH or at least basically from a plastic made from renewable and/or biodegradable materials whereby the plastic made from renewable and/or biodegradable materials is a bio-polymer, in particular PLA, whereby PLA means in particular poly-D-lactic acid (D-PLA), poly- L-lactic acid (L-PLA) and mixtures thereof.

Such surface layers proof a tight package which can withstand water, humidity, oils and other substances which are especially contained in food and drinks. The surface layer itself is biocompatible and should be at least mostly biodegradable.

Further it has proved to be very advantageous if the primer is solvent-based or solvent-free and provided as a solution or dispersion in a solvent or water and the primer could be made from renewable materials and/or can be biodegradable.

Such a primer is also biocompatible.

A veiy advantageous embodiment of the invention is given, if the primer is based on starch, lignin, natural rubber, casein, dextrin, nitrocellulose, cellulose, cellulose acetates, bone glue, fish glue, soya and/or gelatin, their mixtures and variations and/or that the primer is based on a biopolymer and/or that the primer is based on polymer made from starch, thermoplastic starch, poly-lactic acid (PLA), non-crystalline PLA, crystalline PLA, whereby PLA means in particular poly-D-lactic acid (D-PLA), poly- L-lactic acid (L-PLA) and mixtures thereof, polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB), biodegradable polyesters and/or copolyesters, aliphatic copolyesters, aromatic copolyesters and/or aliphatic-aromatic copolyesters or their blends and/or that the primer has functional groups on the basis of thermoplastic aery Is, vinyl acetate ethylenes (VAE), ethylen vinyl acetates (EVA), polyvinyl acetates (PVAc), ethylenvinylalcohols (EVOH), polyvinyl alcohols (PVOH), polyamides (PA), polyesters (PES), polyethylentereplitalates (PET), cellulose and/or mixtures or blends of these materials with other materials.

All these primers have proven to have good bonding properties and can be disposed unproblematically.

Another very advantageous embodiment of the invention is that the primer is sealable, cold sealable, heat sealable, ultrasonic sealable and/or laser sealable with direct or indirect methods.

With this feature a seam can be easily formed.

According to the invention it has also proven to be advantageous that the side of the paper or cardboard substrate provided with the surface layer forms the inside of the packaging and that the packaging can be a paper cup which can be produced with the winding method and has a wall with a side seam and a bottom or that the packaging is in some way a folded or deep-pressed cardboard and/or paper packaging, whereby also multilayered packages can be formed which have at least one layer showing the substrate layer.

With this a easy and effective way of forming tight packages is given. Also multilayered packages can be formed which are often used in form of double walled or triple walled cups for hot drinks like coffee. Further other insulated packages can be made.

Further it is advantageous if the inside and/or outside of the packaging is provided with a printing. By such a printing decorative elements can be arranged as well as information and advertisements. It is also possible that the printing itself forms a humidity or liquid resistant coating, which can for example be arranged on the outside of the packaging.

Further it is very advantageous if the primer is provided by a printing method for forming a seam on the side not provided with the surface layer of the substrate or for the application of the surface layer on the side of the substrate to be provided with the surface layer.

This is a easy and effective way to provide the primer in the areas where it is needed.

Another very advantageous embodiment of the invention is given if the primer layer is limited to the seam area or is arranged directly in the seam and away from the inner edge of the seam whereby the primer can be arranged at a outer edge of the substrate and can cover the edge of the substrate.

By this embodiment the primer is limited to the essential areas on the packaging. Therefore costs are hold low even if the primer used is expensive. If the edge of the substrate layer is covered by the primer a additional protection is given. The filling can not enter the substrate layer.

A further advantageous embodiment is given if the primer layer has a weight between 1 and 10 g/m ² , preferably between 2 and 6 g/m ² whereby the primer is provided over the whole surface or is provided partially on the uncoated side of the substrate whereby the primer can be provided multilayered with different materials used for each layer and whereby the primer layer can be provided with flourescent or other pigments.

Such a thin application of the primer is sufficient. With additional pigments the primer application can be marked visibly or invisibly. Another very advantageous embodiment is given if the primer or at least one primer- layer has barrier properties against oxygen, humidity, steam, liquids and/or other substances.

By such a embodiment the primer can have a dual functionality.

Further it is very advantageous if the surface layer is lined, extrusion coated or laminated whereby the surface layer can be a multilayer construction.

This is a effective way of providing the surface layer also if a multilayer construction is used.

A advantageous further development is also given if at least part of the layers of the surface layer is biodegradable and/or is produced of renewable materials and/or consists of at least partly of a biopolymer, in particular a PLA polymer to an extent of greater than 50 percent.

According to this the whole package can be disposed with compostable waste.

It is very advantageous if the surface layer shows a grammage between 10 and 40 g/m ² , especially between 15 and 25 g/m ² .

Such thin surface layer is thick enough for achieving the desired properties of the packaging.

Another very advantageous further development of the invention is given if the packaging is made from paper, cardboard, carton, moulded fiber, nonwoven fabric, fabric, plastics, in particular from renewable and biodegradable raw materials, whereby the fiber containing materials can be made from virgin and/or recycled fibers. With this embodiment the whole packaging is compostable and/or biodegradable. Further it could be made from recycled fiber materials.

In the drawings a embodiment of the invention is shown.

Fig. 1 a blank for a side wall of a wound paper or carton cup,

Fig. 2 a complete paper cup,

Fig. 3 a intersection through a seam of the side wall, and

Fig. 4 a detailed view of a seam of the side wall.

1 identifies in Fig. 1 a blank, which forms the side wall of a paper cup.

On the outer side of the side wall a printing 3 can be arranged, which contains informations e.g. regarding the filling, advertisements, design objects or the like.

The side wall 1 is wound along its length in such a manner that the side edges are overlapping. These side edges are bonded together to form a tight seam.

The side wall 1 can consist of paper, cardboard or carton, made from virgin and/or recycled fibers. The material should have preferably a grammage between 170 and 350 g/m ² . Due to this relatively thick material the side wall has good stability properties.

Further the side wall of the cup could be made from moulded fiber, non wovens or even plastic materials or the like, all made from new and/or recycled materials. The side wall 1 is provided on the inner side with a single- or multi-layer plastic coating 7, which is made from a biopolymer, especially PLA. At least 50 percent of biopolymer respectively PLA should be contained in the coating 7. The plastic coating can be applied by first applying a tie layer onto the substrate layer and afterwards applying the plastic layer. It is also imaginable that a second plastic layer, arranged between the plastic coating 7 and the substrate layer, is used as tie layer. This second plastic layer can be first combined with the first plastic layer and afterwards both can be bound to the substrate layer for example by lamination. Extrusion coating is also imaginable. Several further layers could be combined by a coextrusion process.

As PLA D-PLA, L-PLA and mixtures thereof can be used.

The plastic coating has a grammage between 10 and 40 g/m ² preferably between 15 and 25 g/m ² . Such a thin coating is sufficient to avoid that humidity, liquids, oils and the like are arriving at the substrate layer. Humidity, liquids, oils and the like are not absorbed by the substrate layer as a result. Further the costs for the coating are kept low. Tt is imaginable that the coating also possesses barrier properties which could for example be generated by additional layers. The barrier layers are preferably arranged between the PLA layer and the substrate layer. The barrier layers could have barrier properties against special liquids, oils, fats or other ingredients of the filling. Further there could be a barrier layer or barrier layers to protect the filling against disadvantageous environmental conditions, e.g. against oxygen.

Additionally it should be considered when choosing the coating materials that the should be heat resistant for coffee cups for example.

The coating 7 should biodegradable at least in certain environmental conditions. Biopolymers, plastics containg biopolymers to a large extent, especially PLA or plastics containing PLA to a large extent can not be joined and/or bonded by common methods like heatsealing with a paper or cardboard. Therefore often a second coating had been applied at least in the area of the seam on the uπcoated side of the side wall 1 , which was normally also PLA. Unfortunately there had been several problems with this. Especially positioning of such coatings was problematic to control. According to the present invention a primer 6 is provided in the areas of the seam 5. Such a primer can be applied by normal printing methods, e.g. flexographic printing. The primer 6 can be applied in solvent-containing or water- containing form.

This primer adheres on one side very good on the paper respectively cardboard and on the other side it could be bound with the PLA plastic coating 7 by common sealing methods.

The primer 6 can be based on renewable raw materials like starch, lignin, natural rubber, casein, dextrin, nitrocellulose, cellulose, cellulose acetates, bone glue, fish glue, soya and/or gelatin, their mixtures and variations. It is also imaginable that the primer 6 is based on a biopolymer. Further the primer 6 can be based on polymers made from or have functional groups of or made from starch, thermoplastic starch, poly-lactic acid (PLA), non-crystalline PLA, crystalline PLA, whereby PLA means in particular poly-D-lactic acid (D-PLA), poly-L-lactic acid (L-PLA) and mixtures thereof, polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB), biodegradable polyesters and/or copolyesters, aliphatic copolyesters, aromatic copolyesters and/or aliphatic-aromatic copolyesters or their blends.

Further the primer 6 can have functional groups on basis of thermoplastic acryls, vinyl acetate ethylenes (VAE), ethylen vinyl acetates (EVA), polyvinyl acetates (PVAc), ethylenvinylalcohols (EVOH), polyvinyl alcohols (PVOH), polyamides (PA), polyesters (PES), polyethylenterephtalates (PET), cellulose and/or mixtures or blends of these materials with other materials. The primer is sealable by common methods e.g. cold sealable, heat sealable, ultrasonic sealable, laser sealable.

With all these primers 6 excellent results in respect to stability and tightness of the seam had been achieved. Further all these primers 6 can be easily applied. It is imaginable that they could be applied with a printing method together with the printing 3 or as a separate step or colour layer of the normal printing method used for the printing 3.

The primer 6 is selected according to the bonding properties but also according to heat resistance if the packaging should be used for hot fillings.

The primer 6 is applied with a grammage between 1 and 10 g/m ² , especially between 2 and 6 g/m ² .

The primer 6 is only applied in the areas where it is needed, especially in the seam area 5.

The primer 6 is only a very small fraction of the total weight of the packaging. Respectively the primer 6 must not necessarily be biodegradable. But it is desired and aspired. Nearly all above mentioned primers 6 are biodegradable and made from renewable raw materials.

Further the primer 6 can itself consist of several layers. It is imaginable that first a primer is applied which binds exceptionally to paper or carton. As second layer another primer can be provided which has very good bonding properties against PLA.

It is further imaginable that multilayered prefabricated primers e.g. with special printing technologies can be provided on the side wall 1. The primer 6 can -as shown in the figures- be arranged inwardly against the outer edges of the side wall 1. With this a contact between the primer 6 and the filling is avoided. But it is also imaginable that the primer 6 is arranged directly beneath at least the inner edge of the side wall 1. Tt is also possible that the primer 6 goes around this edge to avoid direct contact between the filling and the substrate layer. With this leakages are avoided just as well as entering of liquid is avoided in the substrate layer.

Further it is imaginable that the primer 6 is not only applied partly on the outer side of the side wall 1. It could also be applied on the whole area. Then the primer 6 can also be used as protective layer, as barrier layer or the like. A multilayer construction of the primer 6 is imaginable. It is also possible that all layers of the primer 6 are only applied in the seam area.

The seam is formed by common joining methods.

Especially in production of paper cups often direct or indirect heat sealing methods are used. These methods can be used also for cups according to the present invention. A seam can be made with hot air, flame sealing method, or laser sealing. Hot plungers , ultrasonic sealing and inductive sealing can also be used.

When forming the seam the PLA and the primer is molten. Both are bonded together firmly.

Further the seam can be formed by cold seal methods.

The present invention proposes a packaging which is produced nearly wholly or really wholly from biodegradable and/or renewable materials. Small amounts of primer components which are not biodegradable and/or not made from renewable materials are negligible. According to the present invention also multilayered and/or isolating packages like double or triple wall cups can be built. Packages, having isolation properties are often used for cups designed for containing hot drinks like coffee.

A packaging made according to the present invention is ecological.