Container for holding food, method for producing such a container, food unit comprising such a container and method for producing such a food unit

Abstract

Container for holding foodstuffs, with a container body (1) made of ceramic, porcelain, glass or metal, comprising a base (2), one or more side walls (3) and a circumferential upper container edge (4), characterized in that a circumferential plastic element (12), the upper side (14) of which is exposed, is attached to the container edge (4) by means of an adhesive (11).

Description

The invention relates to a container for receiving foods, having a container body consisting of ceramic, porcelain, glass or metal, comprising a base, one or more side walls and a circumferential upper container edge.In many areas of daily life, foods of various types are introduced into containers and the container is then sealed with a sealing film, so that the food is protected. Such film-sealed containers or food units are found, for example, in supermarkets, but also in the care sector. Usually, to form such a food unit, containers made of plastic are used, which allow a sealing film, likewise made of plastic, to be bonded or welded to the plastic container in a sealing method. This allows a correspondingly tight bond, although the sealing film can be torn off if necessary to open the container. Although such plastic containers can be recycled in the meantime, when using such a food unit, the container first of all together with the likewise recyclable sealing film is produced as waste. The use of containers of ceramic or porcelain or glass or metal which can be used multiple times is not possible, since a corresponding bond of the plastic sealing film to the ceramic, porcelain, glass or metal body is not possible.The invention is based on the problem of specifying a container made of ceramic, porcelain, glass or metal which is suitable for use in the context of a film seal.To solve the problem, it is provided according to the invention in a container of the type mentioned at the beginning that a circumferential plastic element, the upper side of which is exposed, is fastened to the container edge by means of an adhesive.The ceramic, porcelain, glass or metal container according to the invention has a container body manufactured from this material, with a base and one or more side walls. If the container is round or oval, only one encircling, circular-ring-shaped or oval side wall is provided, and in the case of a polygonal, for example rectangular container, four side walls are accordingly provided. According to the invention, a plastic element running around the entire edge is fastened to this container edge by means of a suitable adhesive, the upper side of which element is exposed. In a first embodiment, the container edge can be planar, i.e. unprofiled, so that the plastic element is placed on the planar edge surface. Alternatively, according to the invention, the one or more side walls can be profiled in a special manner at their free edge. According to the invention, the container edge can be provided with an upwardly open, encircling groove, i.e. that this round, oval or polygonal encircling groove is formed at the upper container end. According to the invention, a plastic element is accommodated on the container edge or in this groove by means of a suitable adhesive, which element runs around along the entire container edge or the entire groove. On the container rim or in the groove, therefore, such a one-piece plastic element, which can also be referred to as a plastic frame, is placed or inserted and firmly connected to the container body via the adhesive. The plastic element serves as an interface component for attaching a sealing film to the container after it has been provided with a food in a sealing process and for sealing the container and thus the food in an airtight manner. This is because the plastic element offers a corresponding material interface at which a cohesive bond between the plastic sealing film and the plastic element is made possible in the sealing process which takes place at an elevated temperature, for example of approximately 150-180° C. In order to achieve this, the upper side of the plastic element is exposed or, if provided, the plastic element protrudes slightly from the groove, i.e. protrudes slightly with a circumferential upper side, which is preferably planar, so that a sealing film to be applied comes into contact exclusively with the protruding upper side of the plastic element and a materially bonded sealing bond can be achieved there.Within the scope of the use of such a food unit, consisting of the container with introduced food and film welded on, the sealing film can be torn off easily for opening the container, wherein the cohesive bond between sealing film and plastic element is released. After consumption of the food, the ceramic, porcelain, glass or metal container to which the plastic element is finally secured in an inextricable manner via the adhesive as described above can be reused without any problems. It is only necessary to clean it accordingly, after which it can be sent to a renewed covering and sealing operation. The use of such a ceramic, porcelain, glass or metal container in the context of the production of such food units is consequently particularly lasting because of the almost arbitrarily frequent re-useability of the container, as naturally also such a ceramic, porcelain, glass or metal container is visually appealing and is much higher in quality, which is desirable in particular in the case of cathetering.The plastic element preferably has a planar top side, i.e. is planar at the interface surface to which the sealing film is welded. This ensures a correspondingly large contact surface between the sealing film and the plastic element, which is equivalent to a correspondingly large, materially bonded connecting surface.Expediently, the plastic element is rectangular in cross section, wherein it is preferably wider than high. It can have a width of 3-4 mm, for example, at a height of the rectangular cross section of 1.5-2.5 mm, for example, wherein these values are only exemplary and not limiting.As already described, the plastic element protrudes slightly out of the groove, i.e. protrudes beyond the groove edges of the container body delimiting the groove on both sides. This protrusion need not be too large, but it should be at least 1 mm, preferably at least 2 mm, i.e. the plastic element consequently protrudes from the groove by at least 1 mm or at least 2 mm.According to a further development, a plurality of protruding spacers can be provided on the plastic element on the side facing the container edge or the groove. These spacers, preferably in the form of small protruding knobs, rest in the assembly position on the planar container edge or, if provided, on the groove base, resulting in a defined plane in which the plastic element runs. In addition, the spacers also serve to bridge any tolerances of the container body which, since it is fired from ceramic or porcelain, always causes a certain shrinkage during the firing, which may possibly lead to local irregularities, in particular in the edge region and thus in the groove region. The plastic element with its upper side must extend flat, so that a flat support surface for the welding plate of the sealing device is provided, via which the sealing film is pressed onto the plastic element and thermally welded. The spacers fulfil the task of absorbing or bridging these tolerances. At the location at which the container body has the lowest tolerance, the corresponding spacer rests on the container edge or the groove base. At positions with a greater deviation, on the other hand, the plastic element floats. This ultimately has the result that the plastic element or its upper side runs exactly in one plane, which allows the best possible welding of the sealing film.In this case, the spacers are provided at least in the region of the corners in the case of a plastic element having a rectangular shape, while the spacers are provided distributed equidistantly over the length in the case of a plastic element having a circular shape.The plastic element itself is preferably embedded in the adhesive in a floating manner at least in sections, regardless of whether spacers are now provided or not. That is to say that the plastic element can apply local to the groove base, but does not have to be accommodated in a floating manner in the adhesive, which ensures the above-described flatness of the upper side.The groove, if provided, is preferably wider than the plastic element, preferably by at least 1 mm, in particular by at least 2 mm, which facilitates the insertion of the plastic element.The plastic element itself can consist of various plastics suitable for a film sealing method, that is to say plastics which can enter into a corresponding cohesive bond with the sealing film used. Preferably, a plastic element made of polypropylene (PP) or polyethylene terephthalate (PET) is used. The plastic element can consist of only one plastic material, but it would also be conceivable to produce the plastic element from, for example, two different material layers, a first material layer facing the groove base, which for example allows improved adhesion to the adhesive, and a second material layer forming the upper side, which allows improved adhesion to the sealing film.According to a particularly advantageous development of the invention, it is provided that the adhesive is elastic in the cured state. The plastic element is consequently fixed firmly in the groove via an elastic adhesive, but is slightly movable within the scope of the elasticity of the adhesive. This mobility allows further tolerance compensation, since if the sealing film is pressed onto the plastic element via the welding plate during welding, the plastic element can also give way locally if necessary, which ensures optimum contact of the plastic film on the entire surface of the top side. This means that any unevennesses of the groove surface or of the groove base can be compensated for in an optimum manner, in particular if the plastic element is supported towards the groove base via a somewhat thicker adhesive layer, that is to say is adhesively bonded in a correspondingly floating manner.Particularly preferably, a silicone-based compound is used as adhesive, which in particular has the elastic properties described above in the cured state. The compound is preferably a 1K silicone, i.e. a silicone curing without additional curing agent or cross-linking agent. An example of such a silicone is, for example, the silicone potting compound TB 90N from Tomabond GmbH. This silicone is a highly transparent, tension-resistant casting compound which is suitable in particular for food use and which is distinguished by good adhesion to material surfaces, in particular ceramic or porcelain, which ensures a correspondingly strong adhesive bond. The silicone also exhibits good chemical resistance and resistance to ageing, which is advantageous in particular for permanent reuse, in which intensive cleaning always takes place. The silicone cures by a chemical reaction with atmospheric moisture.In addition to the container itself, the invention relates to a method for producing a container of the type described above, having the following steps:providing a container body comprising a base, one or more side walls and a circumferential upper container edge,applying the adhesive to the container edge,inserting the plastic element into the adhesive,curing of the adhesive.In a development of the method, the following steps are provided:providing a container body (1) comprising a base (2), one or more side walls (3) and a circumferential upper container edge (4), wherein an upwardly open circumferential groove (6) is provided on the container edge (4),introducing the adhesive (11) into the groove (6),inserting the plastic element (12) into the groove (6),curing of the adhesive (11).The starting point is the container body made of ceramic, porcelain, glass or metal with either a flat container rim or with the groove formed thereon and running around the upper container rim. The adhesive is introduced onto the planar edge or into this groove, optionally after prior cleaning with a suitable cleaning agent, which is preferably a compound based on a silicone, in particular a 1K silicone. The adhesive can be introduced manually or mechanically. The frame-like plastic element is then pressed into the still fluid adhesive, i.e. if present inserted into the groove, wherein this insertion can likewise take place manually or mechanically. The plastic element is correspondingly embedded by the adhesive depending on the amount of adhesive agent or filling degree of the groove, which allows a sufficiently firm bond. In this case, the plastic element is introduced in such a way that, when a groove is formed, it always protrudes from the groove in a defined manner, i.e. it protrudes beyond the two groove edges which define the upper container edge. In any case, the upper side of the plastic element is exposed and forms an interface for the sealing film to be welded on. After the plastic element has been inserted, the adhesive cures, wherein the curing time can be between a few minutes and a few hours, depending on the adhesive used.The groove is preferably filled with the adhesive to an extent of at least 50% of its volume, in particular to an extent of at least 70% of its volume. This ensures sufficient embedding of the plastic element to be inserted.The plastic element itself can be treated with plasma before the placement. This plasma treatment can achieve activation of the surface for better connection to the adhesive, i.e. preferably the silicone compound.Preferably, the plastic element is pressed into the adhesive by means of a pressure plate, i.e. with a surface element which presses in a defined manner onto the entire upper side of the plastic element. This pressure plate can be guided manually, but preferably mechanically, so that automated insertion results.The plastic element used is preferably one made of polypropylene or polyethylene terephthalate, the plastic element preferably consisting only of polypropylene or polyethylene terephthalate. Alternatively, plastic elements made of other plastics can also be used, as long as they form a correspondingly strong welded bond to the plastic sealing film.The invention further relates to a food unit comprising a container of the type described above, into which one or more foods are introduced, and which is closed by a sealing film attached to the plastic element such that it can be torn off in a sealing method. The food unit therefore comprises, in addition to the container according to the invention, also one or more foods introduced therein and the sealing film welded thereon. The food unit is thus the final unit as it is finally dispensed to the consumer.Finally, the invention also relates to a method for producing a food unit of the type described above, having the following steps:providing a container of the type described above,applying a sealing film by means of a film sealing device to the plastic element, forming a cohesive connection of the sealing film to the plastic element.The sealing, i.e. the application of the sealing film, can optionally take place under nitrogen, with which the volume of the interior of the container of the final food unit is filled.Further advantages and details of the present invention are evident from the exemplary embodiments described below and on the basis of the drawings. The following are shown: FIG. 1 is a sectional view through a container body serving for the production of a container according to the invention, FIG. 2 is a partial view in plan view of the container body from FIG. 1, FIG. 3 is a sectional view corresponding to FIG. 1 of a container according to the invention with adhesive introduced into the groove of the container body and plastic element inserted, FIG. 4 is a partial view corresponding to FIG. 2 of the container from FIG. 3 , FIG. 5 shows a sectional view corresponding to FIG. 3 after introducing a foodstuff into the container and applying a sealing film to form a foodstuff unit, FIG. 6 shows a partial view corresponding to FIG. 4 of the food unit from FIG. 5, FIG. 7 is a plan view from below of the plastic element to be inserted into the groove, FIG. 8 shows a side view of the plastic element from FIG. 7 FIG. 9 shows a sectional view through a container body of a second embodiment serving for the production of a container according to the invention, FIG. 10 shows a sectional view corresponding to FIG. 9 of a container according to the invention with adhesive applied to the flat container edge and inserted plastic element, FIG. 11 is a partial view in plan view of the container from FIG. 10, FIG. 12 shows a sectional view corresponding to FIG. 10 after introducing a foodstuff into the container and applying a sealing film to form a foodstuff unit.FIG. 1 shows a sectional view of a container body 1, FIG. 2 shows a partial view in a plan view of the container body 1, the container body 1 having a base 2 and a total of four side walls 3, of which only three are shown in the present case on the basis of the sectional view. The side walls 3 form an upper, encircling container edge 4 which is spread horizontally over an edge section 5 projecting to the side. On the container edge 4 or the edge section 5, a circumferential groove 6 is formed, which is bounded on both sides by corresponding edge webs 7 and downwards by a groove base 8. The groove 6 is open at the top. It completely circulates around the rectangular container 1, as also shown in FIG. 2. In the region of the corners 9, the container is rounded, which applies equally to the container edge 4 and thus necessarily also to the course of the groove 6.The groove 6 is, for example, 1.5-2 mm deep, with a width of 6-7 mm. The dimension of the groove is preferably always the same for different container sizes, since it serves to accommodate a plastic element which forms an interface for arm welding of a sealing film, wherein this interface should always be of comparable design independently of the container size.FIGS. 3 and 4 show the finished container 10 comprising the container body 1 from FIGS. 1 and 2, wherein an adhesive 11, preferably a silicone-based compound, in particular a 1K silicone, is introduced into the groove 6, wherein, within the scope of this introduction, the groove 6 is approximately 70% filled with the fluid adhesive 11. The adhesive 11 can be introduced manually, but preferably automatically via a suitable dispensing device. A plastic element 12 which is frame-like and whose shape corresponds to the geometry or the course of the groove 6 is placed in the still fluid adhesive 11 and pressed into the adhesive 11 so that the adhesive 11 embeds the plastic element 12 at the bottom and at the side, as FIG. 3 shows, but also FIG. 4. The plastic element 12 is preferably made of polypropylene or polyethylene terephthalate and has a substantially rectangular cross section, wherein a plurality of spacers 13, for example round knobs, optionally protrude on the underside, which rest on the groove base 8, for example locally at the locations at which no or only slight tolerances are present. This means that a tolerance compensation or a compensation of any unevennesses of the groove base 8 is possible via these spacers 13 or at least a part thereof. This serves to ensure that the upper side 14 of the plastic element 12 runs absolutely flat. This is because the upper side 14 forms the sealing surface of the plastic element 12 to which a sealing film is to be fastened by a thermal sealing method. The upper side 14 of the plastic element 12 which is rectangular in cross section is already planar, it being possible by means of the described tolerance compensation to ensure that the upper side 14 runs overall in one plane over the entire extent of the plastic element 12. The plastic element 12 is preferably introduced or inserted via a corresponding pressure plate, with which the plastic element 12 is pressed into the adhesive 11 and thus into the groove 6 in a defined manner, wherein this insertion can be carried out manually or preferably automatically.As described, the adhesive 11 is preferably a silicone-based compound, i.e. a silicone adhesive. This adhesive preferably cures elastically, i.e. the cured adhesive has intrinsic elasticity. This in turn means that the plastic element 12 is movable relative to the container 1 in a certain manner. This low mobility offers a further tolerance compensation possibility, since the plastic element 11 can yield somewhat due to pressure during the application of the sealing film, in which the sealing film is pressed with a certain pressure onto the plastic element 11. Since the sealing film is pressed on by means of a suitable heating plate, a uniform pressure is given, which the plastic element 12, which is embedded in the adhesive 11 in the regions in which it does not lie on the groove base 8 with a spacer 13, and consequently in a floating manner, can follow.In the mounting position shown in FIG. 3, the plastic element 12 clearly protrudes somewhat from the groove 6, i.e. protrudes beyond the edge webs 7, so that the upper side 14 represents the uppermost plane with which the sealing film comes into contact during sealing, and to which the sealing film can be fastened. For this purpose, the plastic element 12 has a corresponding dimension. It should have a width of approximately 2.5-5 mm, so that it can be inserted into the groove 6 without any problem from the width point of view. The thickness of the plastic element 12 should be at least 2 mm, with a somewhat greater thickness naturally being present in the plane of a spacer 13. A spacer 13 has a length of 0.75-1 mm, for example. A basic thickness in the rectangular cross-sectional area of 2 mm is sufficient, due to the quasi-floating embedding in the adhesive 11, to ensure a sufficient protrusion of, for example, 1-1.5 mm.An example of such a plastic element 12 is shown in FIGS. 7 and 8. As can be seen, the shape of the plastic element 12 corresponds to the shape and the course of the groove 6, and it is only slightly narrower. In FIG. 7, which shows a view of the underside, which points toward the groove base 8, the spacers 13, which are provided primarily in the region of the corners in the present case, where the container body 1 usually has the smallest tolerances, i.e. the plastic element 12 is supported in the region of the corners via the spacers 13 toward the groove base 8. In the other regions, the plastic element 12 is floating in the adhesive 11, and the spacers 13 can likewise be seen easily in the side view shown in FIG. 8.The container 10 according to the invention is configured with the fastening of the plastic element 12 for use in a film sealing method. Within the scope of this, a food 15 is introduced into the container 10, which is shown only by way of example in FIGS. 5 and 6. The container 10 is then introduced into a film sealing machine in which a sealing film 16 is thermally welded to the upper side 14 of the plastic element 12 via a cohesive connection. This is done by means of a heating plate with which the sealing film 16 is pressed against the upper side 14 of the plastic element 12. At elevated temperature, for example a sealing temperature of 170° C., a material bond occurs between the sealing film 16 and the plastic element 14, so that the interior in which the food 15 is accommodated is completely hermetically sealed. The interior space may be filled with nitrogen during sealing. The cohesive connection between the sealing film 16 and the plastic element 12 is releasable, i.e. if necessary, i.e. if the foodstuff 15 is to be consumed, the sealing film 16 can be torn off without problems. Consequently, FIGS. 5 and 6 show the food unit 17 which can be formed using the container 10 and introducing the food 15 with the welding of the sealing film 16.The sealing film 16 is a suitable plastic film which can consist only of one plastic material, but usually consists of a plurality of different plastic layers only a few micrometers thick. Frequently, a plastic layer of polyethylene (PP) is applied to which a layer of ethylene polypropylene (EVA) is applied. The layer composite can also contain a further polymer layer, for example made of polyethylene terephthalate (PET), wherein in principle the mentioned plastic layers and their number are not exhaustive, but rather other plastic layers or materials can also be used as long as the sealing film forms a firm bond with the plastic element 12.FIGS. 9-12 show another embodiment. Here, see FIG. 9, a container body 1 with a planar container edge 4 with a widened, planar edge section 5 is used. As shown in FIGS. 10 and 11, the adhesive 11 is applied to this flat container edge 4 or edge section 5, into which the plastic element 12 is then inserted and embedded. The plastic element 12, preferably likewise provided with spacers 13, also projects here somewhat out of the adhesive 11, so that it is exposed with its top side 14. After curing, a container body 1 is again obtained with a defined interface formed via the plastic element 12 for fastening a sealing film.Such a sealing film is shown in Fig. 12. It is welded onto the upper side 14 of the plastic element 12 so that the food 15 introduced into the container body 1 is hermetically sealed.Detailed explanations made with respect to the exemplary embodiment according to FIGS. 1 to 8 apply equally also to the example according to FIGS. 9 to 12, insofar as they do not relate to the groove.In the examples shown, the container body 1 is made either of ceramic or porcelain (both glazed or unglassed), or of glass or metal.

Claims

Container for receiving foods, having a container body (1) consisting of ceramic, porcelain, glass or metal, comprising a base (2), one or more side walls (3) and a circumferential upper container edge (4), characterized in that a circumferential plastic element (12), the upper side (14) of which is exposed, is fastened to the container edge (4) by means of an adhesive (11).Container according to claim 1, characterised in that an upwardly open, encircling groove (6) is provided on the container edge (4), in which groove the plastics element (12) encircling the groove (6), the upper side (14) of which is exposed and projects out of the groove (6), is fastened by means of the adhesive (11).Container according to claim 1 or 2, characterised in that the plastic element (12) has a planar upper side (14).Container according to claim 3, characterised in that the plastic element (12) is rectangular in cross-section.Container according to one of the preceding claims, characterized in that the plastic element (12) has a thickness of at least 1.5 mm, preferably of at least 2.5 mm.Container according to claim 5 and claim 2, characterised in that the plastic element (12) projects from the groove (6) by at least 1 mm, preferably by at least 2 mm.Container according to one of the preceding claims, characterized in that a plurality of protruding spacers (13) are provided on the plastic element (12) on the side facing the container edge (4).Container according to claim 5, characterised in that the spacers (13) are provided distributed equidistantly over the length in the case of a plastic element (12) having a rectangular shape at least in the region of the corners and in the case of a plastic element (12) having a circular shape.Container according to one of the preceding claims, characterized in that the plastic element (12) is embedded in the adhesive (11) in a floating manner at least in sections.Container according to one of the preceding claims and claim 2, characterised in that the groove (6) is at least 1 mm, preferably at least 2 mm wider than the plastic element (12).Container according to one of the preceding claims, characterized in that the plastic element (12) is made of polypropylene or polyethylene terephthalate, at least in the region forming the upper side (14).Container according to one of the preceding claims, characterized in that the adhesive (11) is elastic in the cured state.Container according to one of the preceding claims, characterized in that the adhesive (11) is a silicone-based compound.Container according to claim 13, characterised in that the compound is a 1K silicone.Method for producing a container according to one of the preceding claims, having the following steps: - providing a container body (1) comprising a base (2), one or more side walls (3) and a circumferential upper container edge (4), - applying the adhesive to the container edge (49, - inserting the plastic element (12) into the adhesive (11), - curing the adhesive.Method according to claim 15, with the following steps: - providing a container body (1) comprising a base (2), one or more side walls (3) and a circumferential upper container edge (4), wherein an upwardly open circumferential groove (6) is provided on the container edge (4), - introducing the adhesive (11) into the groove (6), - inserting the plastic element (12) into the groove (6), - curing the adhesive (11).Method according to claim 16, characterised in that the groove is filled to at least 50% of its volume, in particular to at least 70%, with the adhesive.Method according to one of Claims 15 to 17, characterized in that the plastic element (12) is treated with plasma before the insertion.Method according to one of Claims 15 to 18, characterized in that the plastic element (12) is pressed into the adhesive (11) by means of a pressure plate.Method according to one of Claims 15 to 19, characterized in that a plastics element (12) made of polypropylene or polyethylene terephthalate is used.Method according to one of Claims 15 to 20, characterized in that the adhesive (11) used is a composition based on a silicone, in particular a 1K silicone.Food unit comprising a container according to one of claims 1 to 14, into which one or more foods are introduced, and which is closed by a sealing film (16) which is attached to the plastic element (12) in such a way that it can be torn off in a sealing method.Method for producing a food unit according to claim 22, comprising the following steps: - providing a container according to one of claims 1 to 14, - applying a sealing film (16) to the plastic element (12) by means of a film sealing device, forming a cohesive connection of the sealing film (16) to the plastic element (12).

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