WO2006097166A1

WO2006097166A1 - Reclosable packaging

Info

Publication number: WO2006097166A1
Application number: PCT/EP2006/001149
Authority: WO
Inventors: Thomas Renger; Jürgen Fett-Schudnagis; Michael Drobnik; Norbert Bialas
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 2005-03-12
Filing date: 2006-02-09
Publication date: 2006-09-21
Also published as: DE102005011500A1

Abstract

The invention relates to a reclosable container consisting of a lower part and of a covering film, either the lower part or the covering film consisting of a multilayered film. This multilayered film consists of an inner layer, which faces the inner portion of the container, of an adhesive layer placed between the inner and outer layer, and of at least one outer layer. The adhesive layer on the surface of the edge of the container or on the surface of the covering film, which is opposite the edge, is comprised entirely or in part of permanently tacky adhesive, and the other adhesive layer is comprised of a laminating adhesive.

Description

COMPRESSABLE PACKAGING

The invention relates to a resealable container for use as a package for sensitive goods, such as food or clean-stored articles of daily needs.

Furthermore, the invention relates to a method for producing such resealable container.

Articles of daily use, such as food, animal feed, but also disposable items, such as disposable tableware or tissue paper often come in portioned form on the market to enable the consumer easier handling and to facilitate the portioning. Examples of portioned foods are sausage, cheese, or snack food, such as pretzel sticks, which are already present in portioned form in the package. The consumer simply has to open the packaging, remove the desired amount of food and then store the remainder until final consumption. The problem, however, is that the reclosure of such packaging is often not possible. As a result, the food remaining in the package will dry out on storage, become unsightly and lose their typical flavor. For durable items, contamination is possible or these items are disordered together. There are packages in which the lid is resealed by mechanical engagement in a circumferential edge. However, such packages have the disadvantage that they have an increased space requirement through this edge and, depending on the design, can also be stacked poorly. In addition, it is often problematic in these packages for non-rigid packaging materials to close the lid and base again.

Other packages achieve reclosability by firmly adhering a multilayer film to a container above an opening, the multi-layer film releasing a permanently pressure-sensitive adhesive (PSA) when ragged, which reseals the lid on the rim the exposed area allows. Such packages are described for example in EP-A 0978460, EP-A 0868368 and DE-A 0160975.

The reclosability is achieved in these cases in that the multi-layer cover film on the side facing the container has a lower film which is easily broken by mechanical stress, on this lower film a PSA is continuously present and laminated thereon at least one further tear-resistant film is. This multi-layer cover sheet is attached to the edges of the container either thermally or via an additional sealant adhesive. When tearing the multi-layer cover film, the upper film is separated in the region of the edge of the container from the lower film, it is to tear the less tear-resistant inner film. Thus, the adhesive layer is exposed directly above the edge and the container is resealable with this adhesive surface.

Disadvantages of this structure are that the tear seam of the cover on the inside of the edge of the container often frayed and looks unclean. Furthermore, the choice of adhesive is difficult, because on the one hand the PSA adhesive permanently connect both films and the closure of the packaging must be guaranteed, on the other hand, an easy tearable should be given. Furthermore, it is known that these P SA adhesives often contain ingredients that are less suitable for food packaging.

It is therefore an object of the present invention to provide a reclosable package consisting of a lower part and a cover film, which shows a firm adhesion of all film constituents above the cover of the opening of the container, wherein the adhesive should not cause any negative influence on the packaged objects , which also ensures an easy exposure of an adhesive in the region of the container edge and there allows one, even with different storage conditions, repeated closeability of the container with the cover.

A further object of the invention is to provide a method for producing a corresponding multilayer film as a cover film for a resealable packaging.

The object is achieved by a resealable container, consisting of a lower part with a molded-up edge and a cover covering the lower part, wherein the cover or the lower part is formed by a multilayer film consisting of at least one outer layer, one the inner part of the container The adhesive layer on the edge opposite cover sheet surface or on the edge surface of the lower part entirely or partially consists of a permanent adhesive adhesive and the adhesive layer of the surface above the opening of the lower part or within the edge of the Lower part consists of a laminating adhesive.

In this case, the resealable container consists of a lower part with an upwardly facing integrally formed edge around the container opening, wherein the container opening including the edge is closed by a cover or can be closed. In one embodiment, the cover film is a multilayer film consisting of at least one outer layer and an inner layer facing the lower part, wherein between outer layer and inner layer an adhesive layer is present, this adhesive layer consists of two different types of adhesive. This multilayer film is with the edge of the base on several pages, usually on all sides by z. B. thermal sealing connected.

The lower part of the packaging may have any shape that is tailored to the intended content. It may be round or polygonal, in particular square, container. Materials for these containers are known and can be selected by those skilled in the art. These can be selected according to the requirements of the content. These containers have an edge formed around the opening. This edge must have such a width, for example 0.5 - 10 mm, that it can be permanently connected to the cover. He should essentially have a smooth surface, in particular he should just be shaped. Corresponding embodiments of the lower part of the container are known and can be taken from the literature.

The cover of the container is done by a multi-layer film designed according to the invention. Individual components of multilayer films are already known. It can be a combination of different single sheets that are linked together. This multilayer film is connected to the container at the edge in a known manner by a seal.

Another embodiment of the invention has the reverse construction. In this case, a lower part is formed from a multilayer film formed according to the invention, while the corresponding cover film comprises a conventional single or multilayer film. Both parts are sealed together. This embodiment, in principle, shows an analogous principle of operation, but the embodiment described above is preferred.

The term "sealing" is generally understood to mean that a soft sealing medium bonds adhesively. Heat input and / or a minimum seal pressure are required for this purpose. Accordingly, a distinction is made between heat-sealing and cold-sealing, whereby the question of which type of sealing is used is, for example, of the materials used, the object to be packaged, for. B. its heat sensitivity, and the nature of the packaging machine is dependent.

Cold sealing employs cold seal adhesives that bond two polymer layers at room temperature under high pressure. Cold seal adhesives are predominantly applied as aqueous dispersions to the polymer to be bonded and are based on rubber and rubber-like polymers, such as PVDC (polyvinylidene chloride), PVAC (polyvinyl acetate) and poly (meth) acrylates.

For heat sealing, heat-seal dispersions, heat-sealing lacquers, hot melt adhesives and films of thermoplastic elastomers and extrusion coatings are used.

Heat seal dispersions are predominantly PVDC, PVAC poly (meth) acrylate or latex-containing dispersions which form sealable, dry and generally transparent coatings after evaporation of the water. In contrast to the heat seal dispersions, organic solvents are used in the heat sealing lacquers using identical or similar polymers. Hot-melt adhesives based on hotmelt adhesives generally contain ethylene-vinyl acetate copolymers as base materials, which are applied to the substrate by roller application or else by extrusion.

Thermoplastic elastomer films and extrusion coatings are also used for heat sealing, often referred to as "weld film". In the context of the present invention, these films are particularly preferably used as the inner layer facing the container interior. In particular, PE (polyethylene) films are preferred as sealing films for sealing.

The multilayer film suitable according to the invention may be a combination of any number of films. The multilayer film is about 20-200 μm thick, preferably 30-160 μm, and particularly preferably 50-120 μm. The AU- The outer layer usually consists of polyethylene terephthalate, polyamide, biaxially oriented polypropylene, polyvinyl chloride or metal foils, for example aluminum, or paper. The thickness of the outer layer is 10 to 150 μm, preferably 20 to 100 μm and particularly preferably 40 to 80 μm. The outer layer is selected so that it is stable at temperatures up to 200 ⁰ C.

In the case of the reverse construction of the composite of known cover film and inventive lower part, the tear-resistant cover film may have a thickness of 10-200 μm. In this case, the lower part consists of a multilayer film constructed according to the invention and may have a thickness of 30-300 μm, preferably a thickness of 50-200 μm.

The side of the multilayer film which is used for sealing or sealing and is referred to as inner layer, is usually made of a polymeric material with low elongation at break and tear propagation resistance. Polyolefins are preferably used as the polymeric material for the inner layer. The polyolefins used for the inner layer include, for example, propylene copolymers, in particular ethylene-propylene-butylene copolymers, ethylene-propylene-butylene terpolymers or mixtures of these polymers.

In a preferred embodiment, the inner layer is made of high density polyethylene. By the term "high density polyethylene" are meant polyethylenes which are largely linear and unbranched. These polyethylenes have crystallization degrees of 60-80% and a density of about 0.94-0.965 g / cm ³ . The melting point of the polymeric material for the inner layer is generally 80-160 ° C, preferably 100-140 ° C. Such materials may preferably be heat-sealed.

The thickness of the inner layer is 1 to 80 μm, preferably 10 to 60 μm and in particular 20 to 50 μm. After sealing, the multi-layer film and the lower part are firmly joined together and a tearing should take place in the inner layer film. Possibly. it is possible to pretreat the inner layer or outer layer film on the side facing the adhesive layer. Within the context of the invention, pretreatment is understood to be processes with which the surface of plastics is changed in order to improve the adhesion to other materials. Methods known to those skilled in the art include, for example, the corona process or the flaming process.

Foils suitable for the invention for the outer layer, as well as usable materials for the edge and the lower part are described in EP 0868368 A, DE 3935480 A, US 4,913,307, DE 0160975 A and US 5145737. The skilled person can make a corresponding selection. There may also be additional layers as an outer layer and form a multilayer outer film. Known composite combinations of multilayer films are, for example:

- Metallized PET / PE / adhesive layer / PE

- PET / adhesive layer / PE

- Aluminum foil / PE / adhesive layer / PE

- PET / adhesive layer / coextruded PET with PE bottom

- PET / adhesive / polyolefin / heat sealing lacquer.

The multilayer film suitable according to the invention is a multilayer film which has at least one outer layer and an inner layer, wherein the inner layer has a lower tear strength than the outer layer. Both layers are bonded together with an adhesive layer. The bonding of the layers is done by laminating. In this case, an adhesive is applied to a layer, preferably the outer layer, and the second layer is then applied and pressed under pressure and possibly elevated temperature. The temperature can be between 30 and 150 ° C.

In the packaging according to the invention, the multilayer film is bonded together with two different adhesives. On the surface opposite the opening of the lower part of the container, a laminating adhesive is applied. Laminating adhesives essentially have the property of bonding two films firmly and flexibly together. Such adhesives are known to those skilled in the art. known. Likewise, such laminating adhesives are known which are suitable for selected applications, for. B. for packaging food or medical articles. Such adhesives are described, for example, in EP 0118065, EP 0150444, EP 0951493, EP 1030869, WO 99/33897, EP 0863935 or EP 0928317. The laminating adhesive is intended to bind the films together more firmly than the tensile strength of the inner layer. Likewise, the seal should be more stable than the tear strength of the inner film.

Laminating adhesives can be used in various forms of application, such as aqueous dispersion, solvent-based or solvent-free adhesive. The chemical composition of such adhesives can be varied within wide limits. Suitable adhesives, which are also approved for use in food packaging, are often based on polyurethanes. This low-monomer polyurethane prepolymers are prepared from polyfunctional alcohols and polyisocyanates. By a suitable reaction, the content of monomeric isocyanates can be lowered. The isocyanates used are the diisocyanates and polyisocyanates known in polymer chemistry. These may be aliphatic, aromatic, monocyclic or polycyclic isocyanates. These may have isocyanate groups of the same reactivity or different reactivity. For example, polyether polyols, polyester polyols, polycarbonate polyols can be used as the polyol component. Mixtures of diols and in small proportions also polyols can be used. The polyols used can be varied within wide limits. By selection and amount of polyols and isocyanates, the viscosity of the polyurethane prepolymers can be varied. Linear or branched prepolymers can be obtained. For example, one-component moisture-curing adhesives can be obtained from such prepolymers. When olefinically unsaturated groups are reacted, curable compositions can also be prepared by actinic radiation. It is also possible to prepare two-component adhesives from isocyanate group-containing prepolymers and a second component which contains isocyanate-functional groups. Suitable adhesives are well known to those skilled in the art and may be selected as appropriate to the present invention. Particularly suitable for the production of the multilayer film for the container according to the invention are laminating adhesives which can be applied by means of a printing unit. These are essentially thin-viscosity laminating adhesives, in particular dispersion adhesives, solvent-based adhesives or solvent-free adhesives.

The viscosity of these laminating adhesives should be between 1 and 10,000 mPas at the application temperature. In the case of solvent-free laminating adhesives, it is preferably 500-3000 mPas, in particular at 30-150 ° C. In the case of solvent-containing laminating adhesives, the viscosity is below 300 mPas, in particular between 1 and 100 mPas at 30 ⁰ C. The viscosity is determined at the intended temperature with a Brookfield viscometer according to ISO 2555, at a viscosity below 100 mPas is according to DIN 53211 measured with the DIN cup. In principle, other higher-viscosity adhesives are suitable. However, a corresponding job opportunity must be given by a printing unit.

The laminating adhesive should be applied to the surface opposite the opening of the container. In one embodiment of the invention, this adhesive is also applied to a part of the surface of the multilayer film opposite the edge. Thus, after sealing, there is a firm bond between the covering film and the container bottom part, since in this case inner layer, laminating adhesive layer, outer layer are stably connected to the edge of the lower part, and only a part of the covering film can be reclosed from the container. Another embodiment of the invention uses only on the directly opposite the opening of the multilayer film, the laminating adhesive, so that the cover can be completely separated from the base.

According to the invention, a permanently tacky adhesive is applied between the inner film and the outer film on the surface opposite the edge of the lower part. These may be pressure sensitive adhesives that are pressure sensitive Adhesive (PSA) are known. Furthermore, other permanently tacky substances are used, such as sub-crosslinked Kaschierklebstoffe. Such permanently adhesive adhesives are known to the person skilled in the art. In particular, however, they are PSA adhesives. These are adhesives that may be applied to a surface when hot, firmly bonded to this surface, with the side of the adhesive that faces away from the substrate permanently having a high level of stickiness.

The preferred pressure-sensitive adhesives, called also "pressure sensitive adhesives" and abbreviated "PSA", are viscoelastic adhesives which remain in solvent-free form permanently tacky at about 20 ⁰ C and adhesive and at low substrate specificity with light pressure immediately on almost all Adhere substrates.

Pressure-sensitive adhesives are applied to the substrate in the form of solutions in organic solvents, as an aqueous dispersion, in a solvent-free form or else as a melt. Preference is given to solvent-containing pressure-sensitive adhesives with aliphalic solvents, for example ethyl acetate or methyl ethyl ketone, if appropriate also hexane or heptane or low-boiling hydrocarbon mixtures.

Pressure-sensitive adhesives which can be used according to the invention are described, for example, in WO 01/14491, WO 98/00471, EP 1189961, US 2001/0044024 A1, US Pat. No. 3,239,478 and US Pat. No. 5,292,842. Low-viscosity, solvent-free or reactive systems are also used as pressure-sensitive adhesives and optionally irradiated with UV or electron beams for post-curing.

As raw materials for pressure-sensitive adhesives serve water-soluble and water-insoluble base polymers, plasticizers, waxes, resins, in particular tackifying resins to improve the adhesion, fillers and auxiliaries such as preservatives, antioxidants, stabilizers and dyes.

The base polymers are generally present in the pressure-sensitive adhesive in a concentration of up to 50% by weight, preferably in a concentration of from 5 to 40% by weight. contain. Furthermore, it is common to add at least one tackifying resin in addition to the base polymer, and in some systems the tackifying resin may also be a low molecular weight fraction of the base polymer.

As base polymers for pressure-sensitive adhesives are generally used natural and synthetic rubbers in conjunction with modified natural resins, phenol-formaldehyde resins or hydrocarbon resins. In addition to rubber, polyacrylic acid esters, polymethacrylic acid esters, polyvinyl ethers and polyisobutene types are also frequently used, usually in combinations with natural resins. Such polymers and tackifying resins can be dissolved in solvents. Together with necessary additives thin-viscosity solvent-based pressure-sensitive adhesives are then obtained.

Dispersion adhesives are mainly based on polyacrylic acid ester dispersions or on special vinyl acetate copolymers, wherein the above-mentioned resins are also generally added here. Such pressure-sensitive adhesives in aqueous dispersion may, in addition to the additives known to the person skilled in the art, also contain further small amounts of organic solvents in individual cases. The viscosity can be influenced via the solids.

As a further pressure-sensitive adhesive hot melt adhesives are known. These consist of known base polymers, such as block copolymers, z. Styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene-styrene, ethylene-vinyl acetate polymers; Polyolefins such as polyethylene and polypropylene, especially amorphous propylene-alpha-olefins (APAO); PVAc copolymers, polyacrylates; polyamides; Polyester; Polyvinyl alcohols (PVA), polyurethanes, polystyrene; Polyepoxides, copolymers of vinyl monomers and polyalkylene oxide polymers.

Furthermore, resins, in particular natural resins, are included as a further component. These are, preferably modified, aliphatic, cycloaliphatic, aromatic or alkylaromatic hydrocarbon resins. In addition, waxes may be included in the pressure-sensitive adhesive up to 40% by weight. The wax used may be of natural or synthetic origin. Examples are vegetable waxes, animal waxes, mineral waxes or petrochemical waxes. Plasticizers may also be present in the pressure-sensitive adhesive in a concentration of up to 30% by weight. In addition, the pressure-sensitive adhesive can be accompanied by customary auxiliaries and additives, such as, for example, stabilizers, fillers and / or pigments or antioxidants.

Likewise, radiation-crosslinkable hot melt pressure sensitive adhesives are known. These have generally similar compositions, but the base polymer and optionally further constituents are reactive towards radiation. As a result, if necessary, the application viscosity of the pressure-sensitive adhesive can be lowered, since this is further crosslinked only after application.

Radiation is to be understood here as meaning any type of radiation which causes irreversible crosslinking in the crosslinkable hot-melt pressure-sensitive adhesive layer to be irradiated. Particularly suitable are UV, electron beams, short-wave visible light, but also IR radiation. In the invention preferred ESH or UV irradiation some product properties can be influenced by the radiation dose.

The pressure sensitive adhesives suitable for the subject invention should have a low viscosity. They are to be processed and applied to printing rollers. The viscosity at the processing temperature of the suitable pressure-sensitive adhesives should be between 10 and 10,000 mPas. In the case of hot-melt adhesives, the viscosity should preferably be from 1000 to 10000 mPas, in particular from 1000 to 5000 mPas at the application temperature. In the case of the preferred PSA dispersions or solvent-based pressure-sensitive adhesives, the viscosity should preferably be from 10 to 1000 mPas, in particular from 100 to 500 mPas at room temperature.

Dispersion-containing or solvent-containing pressure-sensitive adhesives in which the viscosity can optionally be adapted to the application conditions via liquid constituents are particularly suitable. In the embodiment according to the invention, the PSA adhesive is preferably applied to the outer layer in the region which is opposite the edge of the lower part. It is important to ensure that laminating adhesive and. Do not mix PSA adhesive together and apply them separately. The order of the order is arbitrary, it can be applied first, if necessary, the laminating adhesive and then the PSA or vice versa. Thereafter, the other film layer is laminated immediately. This happens under pressure and possibly at elevated temperature. If necessary, the so-finished multilayer cover foil can be rolled up and temporarily stored. But it can also be fed directly to the packaging machine as a cover film.

In the second embodiment, a corresponding multilayer film can be produced. However, this is then, for. B. by deep drawing, molded into a container base, wherein the edge portion is formed so that there is the adhesive layer of the PSA. A cover sheet suitable for this purpose can then be produced from the materials known to the person skilled in the art. Upon opening, a permanently tacky layer is then exposed on the edge of the base.

It is essential to the invention that the two adhesives are applied to different surface parts of the multilayer film. Due to the nature of the application method, in particular by printing the adhesive, it is possible to produce a clean, adapted to the contour of the opening of the lower part of the container shape. In this case, the two adhesives can flow together when pressing the film on the edge, but preferably they should not mix with each other, not even during the laminating process. This makes it possible, when tearing the inner foil to obtain a clean, the container opening adapted tear line.

Furthermore, it is preferably possible to leave a small distance between the two adhesives. This should be so low that the adhesion between the two laminated film layers is ensured and at this point no sen or other detachment phenomena. For example, it is possible to produce a distance between 0.01-1 mm, in particular 0.1-0.5 mm.

It is known that the outer part of the multilayer film can be optically designed, for. B. by laminating colored intermediate layers or in particular by printing the outer layer of the multilayer film. This pressure usually occurs on the inner layer facing side of the outer layer. This printing process can be done immediately before the application of Kaschierklebstoffes. The outer film can be printed continuously or it is printed only on the surface of the opening opposite the container. After printing, it is advantageous to firmly connect the ink with the film, for. B. by drying or by a chemical reaction. Thereafter, directly or even after storage, this part of the multilayer film can be supplied to the laminating process.

In order to ensure the most uniform possible connection between outer layer and inner layer, it is expedient to match the layer thickness of the adhesive layer between the two films. The application rate of the laminating adhesive may be 1 to 20 g / m ² , in particular 2 to 10 g / m ² . When a dye layer is printed, the application amount of the dye layer is 0.5 to 10 g / m ² , more preferably 1 to 5 g / m ² . The PSA can be applied with a layer thickness of 1 to 30 g / m ² , in particular 3 to 20 g / m ² . The various adhesives or color amounts are preferably selected so that a substantially uniform layer thickness is obtained on the film surface. The layer thickness of the adhesive layer or adhesive and ink layer is 2 to 30 μm, preferably 5 to 20 μm and particularly preferably 8 to 15 μm.

It can be selected corresponding adhesives that are adapted to the desired properties. The adhesive strength of the films with the Kaschierklebstoff should be greater than that of the composite with the PSA adhesive.

In this case, the Kaschierklebstoff should ensure the most adequate connection of inner layer and outer layer of the multilayer film. Furthermore, the should Laminating adhesive does not affect the printed image on the outer film. It should either be colorless or may have a uniform base color. If necessary, he should not start the dried printing ink again. The PSA adhesive can be selected so that it has as uniform a tear resistance as possible. This can be achieved that the consumer who separates the two films can perform a simple and uniform tearing of the multi-layer film.

Another object of the invention is a method for producing a multilayer film as part of a resealable container. In a preferred embodiment of the invention, the outer film is already printed in color prior to application of Kaschierklebstoffs. This can also be done by one or more anilox rollers. The ink is usually applied on the side of the outer film, which is opposite to the inner film. This ensures that the printed image will not be damaged during further processing. After applying the printed image, this is to be crosslinked or dried. This can be done by known methods by elevated temperature or by chemical reaction or by radiation. On the thus treated outer film, a liquid Kaschierklebstoff is then printed according to the invention, in a size and shape that corresponds to the opening of the resealable container. This printing process, the skilled artisan known printing methods, eg. B. with anilox rollers, smooth rollers, perform with flexographic printing plate. Particularly suitable are anilox rollers or flexographic printing cliché order. It must be ensured that the laminating adhesive has a suitable viscosity.

In another mode of operation, the outer film is already a multilayer film which may already be printed or contains other colored layers in the layer sequence. In this case, the outer film can then, as described above, be coated with a printing unit with the laminating adhesive.

As a second process step, the PSA adhesive is applied to the area provided with the laminating adhesive on the intended surface. This PSA adhesive should be applied to a surface opposite the edge of the base. In this case, the complete edge area can be coated, or possibly a part of the edge area is not provided with the PSA adhesive. The laminating adhesive has then been applied to this part of the edge region in the previous step. This ensures that at this point a permanent connection of the cover with the container base is ensured.

This should be done by the method according to the invention also by the above-mentioned printing method, in particular by an anilox roller or flexographic printing cliché method. The choice of process parameters depends on the PSA adhesive used. The PSA adhesive should have the above-mentioned viscosity at the application temperature, in particular at room temperature of about 20-30 ° C.

In the case of solvent-based adhesives or dispersion adhesives, it is expedient to dry them after application. This can possibly be supported by heat or by passing gases, in particular air.

A particularly preferred mode of operation performs all printing operations in succession, d. H. The multilayer film is first provided with at least one color layer. After a drying process, the laminating adhesive is applied. After a second drying process, the PSA adhesive is applied. Devices for carrying out these printing processes directly one after the other are known to the person skilled in the art.

After application of the two adhesives, the inner film of the multilayer film is laminated. The lamination is done by pressure and may possibly be supported by increased temperature. If radiation-curing laminating adhesives are used, it is necessary that thereafter a curing step, for. B. with UV radiation or electron beam is performed. Such systems and methods for radiation curing of adhesives are known and can be adapted by the skilled person according to the selected adhesive. After laminating the film, it is possible to wind up and store the film, for example. This procedure has proven to be expedient because it gives the adhesive an additional time for complete post-curing and for a good connection of both films. In addition, it is not necessary that the cover film and container bottom are made at the same time. These can then be merged before a final closure of the package. In this case, the objects to be packaged are then introduced into the container, the container provided with a previously cut to the appropriate size cover and sealed with known tools and methods, the cover on the edge of the container.

In the simplest case, the multilayer film consists of an outer layer, an adhesive layer and an inner layer. It is also possible when working according to the invention that the outer film itself consists of several layers. The layers can be made of different materials. The layers may be chosen for visual design or for specific protective purposes of the contents of the package. Thus, by selecting the further layer materials z. B. the ingress of gases or liquids or jets are avoided in the container interior.

The inventive method, it is possible that with known devices, a particularly good connection of the inner foil and outer foil is achieved. The workload is low, the setting of appropriate pressure surfaces for the adhesives is easy to perform and familiar to the expert. A corresponding multilayer film, produced according to the procedure according to the invention, has in the middle of the surface an increased adhesion of outer layer to inner layer, which can not be separated at this point. A separation of the two layers is given in particular in the area of the applied PSA adhesive. This can enable a slight separation of the two films and then expose there the permanently adhesive glue.

By the procedure according to invention a clean boundary line between laminating adhesive and pressure-sensitive adhesive is produced. That leads to a clean tearing of the inner layer along this tear edge is made possible. This leads to a visually appealing and clean-looking separation process. Furthermore, it is possible in the operation according to the invention to optimize both adhesives for their respective application. It is thus possible to select the PSA adhesive so that it has a permanent tack repeatedly, even when stored under different temperatures, eg. B. in the fridge. Furthermore, the laminating adhesive can be selected so that the strongest possible connection of the inner layer and the outer layer is given. Furthermore, it can be selected so that no adverse effects on the interior of the container by constituents of Kaschierklebstoffs, z. B. by migration, are given.

The resealable containers according to the invention are designed so that a repeated closure on the separated surface is possible. They can be designed so that the covering multi-layer film is firmly connected on one side with the container bottom part; but they can also be designed so that the cover is completely removed from the container top and is to be reclosed over the entire edge surface.

The accompanying drawings illustrate the invention.

Figure 1 shows a section through a container according to the invention. In this case, the lower part (1) has an integrally formed upwardly facing edge (2). This edge should be smooth, preferably he should represent a flat surface. Above the edge (2), the cover film is shown in this case as a multilayer film (3). The multilayer film consists of a lower layer (4), for example of a PE material and a PSA adhesive layer (5). This is applied opposite the edge part. Furthermore, the Kaschierklebstoffschicht (6) can be seen, which is located opposite the container opening. Externally, the adhesive layer is covered by the outer layer (7), which may optionally have a printed image (8) on the inside. FIG. 2 shows the top view of a part of the multilayer film. The contour of the edge is applied with the PSA adhesive (5). On the opposite surface of the container, the laminating adhesive (6) is applied. In the case of Figure 2, the entire edge region is covered with the PSA adhesive.

FIG. 3 shows a plan view in which not the PSA adhesive but the laminating adhesive (6) has been applied to a part of the edge region. This ensures when opening that the cover remains connected to the lower part.

FIG. 4 shows a section through an embodiment in which the covering film (3) is any suitable single-layer or multi-layer film. The associated container consists of a multilayer film (8) according to the invention, which was deep-drawn, for example. In this case, the lower part has an edge region, which carries on an outer layer (7) a layer of a PSA adhesive (5), as well as the cover opposite an inner layer (4). Outside the edge, d. H. Container bottom and walls, the adhesive layer consists of a laminating adhesive (6). Thus, even in this case the cover can be separated from the container edge and fastened resealable.

Claims

claims

1. resealable container consisting of a lower part with a molded-up edge and a cover covering the lower cover, wherein the cover or the lower part is formed by a multilayer film consisting of at least one outer layer, an inner part of the container facing inner layer and an intermediate Outer and inner layer lying adhesive layer, characterized in that the adhesive layer on. the cover film surface opposite the edge or on the edge surface of the lower part completely or partially consists of a permanently adhesive adhesive and the adhesive layer of the surface above the opening of the lower part or within the edge of the lower part consists of a laminating adhesive.

2. resealable container according to claim 1, characterized in that Kaschierklebstoff and permanent adhesive are separated from each other.

3. Resealable container according to one of claims 1 or 2, characterized in that the cover film and the edge of the lower part is connected to one another with a sealing adhesive or with a thermal weld.

4. resealable container according to one of claims 1 to 3, characterized in that the laminating adhesive is a dispersion adhesive, a solvent-containing adhesive or a solvent-free adhesive.

5. resealable container according to one of claims 1 to 4, characterized in that the permanently adhesive adhesive is a PSA adhesive in the form of a dispersion or a solvent-based adhesive.

6. resealable container according to one of claims 1 to 5, characterized in that the laminating adhesive has a higher adhesion between the inner film and outer film than the permanent adhesive adhesive.

7. resealable container according to one of claims 1 to 6, characterized in that the cover film is formed as a multi-layer film and the adhesive layer between the inner layer and outer layer relative to a part of the edge of the lower part, in particular one side of the lower part, also consists of Kaschierklebstoff.

8. resealable container according to one of claims 1 to 6, characterized in that the cover film is formed as a multi-layer film and the adhesive layer between the inner layer and outer layer relative to the surface of the edge of the lower part completely consists of a PSA adhesive.

9. A process for producing a multilayer film for producing a resealable container according to claim 1 to 8, characterized in that both parts of the adhesive layer are applied to the inner layer facing side of the outer layer by means of printing units.

10. The method according to claim 9, characterized in that the adhesive layers are applied with an anilox roll or by flexographic printing process.

11.Verfahren according to any one of claims 9 or 10, characterized in that on the outer layer prior to the application of the adhesive layer at least one coloring layer is printed.

12. The method according to claim 11, characterized in that the coloring printing layer and the adhesive layers are applied directly one after the other.

13. The method according to any one of claims 9 to 12, characterized in that first the laminating adhesive and then the permanently tacky adhesive are applied.

14. The method according to any one of claims 9 to 13, characterized in that the layer of permanently adhesive adhesive and the Kaschierklebstoffs optionally together with the printing layer have substantially the same layer thickness.

15. The method according to any one of claims 9 to 14, characterized in that the application viscosities of the adhesives are below 10000 mPas.

16. The method according to any one of claims 9 to 15, characterized in that the adhesives are applied to separate surfaces and do not mix with each other at the boundary.

17 multi-layer film for the production of resealable containers consisting of a lower layer than the container facing inner layer, an adhesive layer and at least one upper layer as an outer layer, characterized in that the adhesive layer partially consists of a Kaschierklebstoffschicht and a permanently tacky pressure-sensitive adhesive layer, wherein the surface part coated with the permanent adhesive pressure sensitive adhesive corresponds to the surface, are joined together by the cover and container bottom.

18. multilayer film according to claim 17, characterized in that they are prepared by a process according to claim 9 to 16.

19. Use of a resealable container according to claim 1 to 8 for the packaging of sensitive goods.