EP0604507B1 - Packaging container for food, a method of manufacturing the container, and a device for carrying out the method - Google Patents

Abstract

Described is a packaging container for food, the container having a deep-drawn tray made of plastic and a lid made of plastic-composite sheet welded to a flange running round the upper rim of the tray. In order to improve the environmental acceptability of the packaging while at the same time simplifying manufacture by conventional packaging machinery, the tray (42) is a thin-walled non-self-supporting flexible-sheet composite system (20) reinforced inside at least in the region of the tray walls, which preferably open out slightly towards the rim, either by a rigid cellulose-containing or wood-pulp-containing insert or by a piece of cardboard (52) coated on both sides with plastic and welded at least at discrete points (118) to the tray (42).

Description

The invention relates to a container for the packaging of foodstuffs, with a thermoformed plastic tray and a cover, preferably welded, in the form of a plastic composite film, which is connected to the top side circumferentially via a flange section, according to the preamble of patent claim 1. The invention also relates to a method for producing a food container according to the preamble of claim 19 and a device for performing a method for producing a food container according to the preamble of claim 27.

Packaging containers of the type described in the introduction are used and used in particular for foods which, owing to their easy perishability, are particularly useful during transport and storage against external influences, such as, for. B. must be protected from excessive temperature or light influences. These containers must therefore not only be sufficiently dimensionally stable and preferably stackable, but also be such that the goods accommodated in the container are preferably hermetic to the environment, in particular to an oxygen-containing one Atmosphere is shielded. Another important criterion for these containers is that the manufacture or processing of the container as well as the filling can be carried out easily, preferably with a space-saving, linearly arranged production system. These production systems have the advantage that they can be constructed modularly, so that the individual workstations can be put together individually, depending on the container to be manufactured, and can thus be used economically.

A conventional container of this type generally consists of two parts, namely a deep-drawn plastic shell with an edge flange on the top and a cover welded to it in the form of a plastic composite film. This plastic composite film regularly has a carrier material layer made of, for example, axially stretched polyamide or polyester, a carbon dioxide or oxygen barrier layer made of ethylene vinyl alcohol (EVOH) and a sealing layer for sealing the cover with the rest of the shell, the sealing layer in the Usually consists of a polyethylene plastic system. The container bottom, ie the deep-drawn plastic shell of the container, is also made from a plastic composite film in the case of higher-quality packaging. To save weight, dimensionally stable films are used, for example polystyrene-based films with a thickness in the range between 700 and 1000 µm. In this case, the polystyrene base layer in turn carries a barrier layer made of an ethylene-vinyl alcohol system and a polyethylene sealing layer facing the cover, which can be thermally welded to the cover. These films are suitable for both negative and positive deformation with and without mechanical pre-stretching of the film. In this way, container shapes of different designs and strengths can be produced with relatively easy-to-control machines, with the retrofitting of the Packaging system when moving from one product to the other can proceed relatively quickly.

When using polyvinyl chloride (PVC) as a mechanically stabilizing layer of the composite hard film, it is possible to reduce the wall thickness of the lower film without sacrificing strength. Nevertheless, even with this selection of materials, a considerable amount of plastic is required per packaging, which, due to the composite structure, has the disadvantage that it can be recycled, i.e. can no longer be recycled.

This problem was recognized early on and attempts were made to construct food packaging in such a way that the proportion of plastic which could no longer be reused could be reduced. For example, a container made of a laminate is known from DE-GM 73 30 156, which has a cardboard layer and at least one side with a polyester cover layer. The main application of this laminate is seen in its use in the manufacture of a container suitable for cooking or reheating food for humans. The laminate is suitably cut for this purpose, then folded and pressed into a shape in the form of a shell, the parts of the surface which are superimposed during the folding being attached to one another by heat sealing. However, such a container cannot be hermetically sealed with a plastic composite film of the type described above, too high oxygen permeability occurring in particular in the corner regions of the container, and a connection to a cover film is not possible due to the lack of an upper edge flange.

In German Patent 1,036,153 an apparatus for producing flat packs is described, which consist of thermoplastic coated paper, which is cut and folded in such a way that there are also lateral, outwardly bent upper packaging edges, over which a cover sheet made of plastic is then welded all around in a sealing station. Even with this known method, it is not possible to produce a container that meets the tightness criteria required for sensitive goods. It should be borne in mind that, in the case of particularly high-quality packaging, evacuation of the package or back-gassing of the package with a protective gas, such as, for. B. carbon dioxide is required. Carbon dioxide has a volatility that is about 4 times higher than that of oxygen. Easily perishable goods can therefore not be stored in a package according to DE-PS 1 036 153. Moreover, the method known from this document cannot be combined with deep-drawing systems of conventional Bauert without making drastic changes to the system.

In the document US-PS 42 57 530 a container for frozen food is described, which is formed by a dimensionally stable shell with a film lined on the inside and a lid sealing film. The shell is made from a pre-cut blank that is only folded at the fold lines to obtain a spatially stable structure. The film subsequently molded into the shell does not lie against the shell wall, so that an air cushion can form. As a result, only a bowl-shaped shape for sealing the container against leakage of liquid is produced.

Finally, attempts have also been made to construct containers according to the preamble of claim 1 in such a way that the shell has both a cardboard part and a plastic part made from deep-drawn plastic film. Examples of such containers are described in GB-PS 1 136 885, GB-PS 1 043 215 and DE-PS 2 034 154. In the case of GB-PS 1 043 215, a container folded from a cardboard blank is connected to a retracted plastic mold via a peripheral, angled flange area. Since the connection between the plastic lining and the cardboard blank is only provided in the flange area, the plastic lining must also be made relatively stiff in this case, since the outside cardboard blank only forms reinforcement and can therefore only be used to a limited extent to stiffen the container shell. After all, this process requires a significant amount of cardboard. An integration of the process into conventional, Standard packaging systems are also not possible.

In the case of the container according to GB-PS 1 136 885, a folded cardboard blank is also lined on the inside with a plastic system, which then also forms the circumferential, angled flange for the attachment of a cover film. In order to be able to pull the plastic film into the negative form with an inserted cardboard blank by negative pressure, the cardboard blank is designed in such a way that it is smaller in area than the outer surface of the inserted plastic film. The stiffening function of the cardboard blank is therefore also relatively limited in this known case.

A complete, stiffening sheathing of a trough-shaped plastic container with a cardboard reinforcement material blank is described in DE-PS 2 034 154. When producing such a container, however, a relatively complex tool is required. First, the cardboard blank is folded into a negative form, which interacts with an upper stamp, by means of which a film web is then pressed into the form. A suction stamp is used to fold in the cardboard blank, which holds the cardboard blank with a relative movement between the suction stamp and the negative form. In order to be able to firmly connect the plastic film to the inner surface of the cardboard blank, a pressure medium is fed into the space between the upper stamp and the molded plastic film by means of the upper die after the plastic die has been molded in, which then provides the final shape of the container and the firm adhesion of the film to the folded blank causes. This manufacturing method can hardly be carried out without major conversion measures with packaging machines on the market according to the preamble of claim 27.

The invention is therefore based on the object to provide a container for packaging food according to the preamble of claim 1, which is characterized in that the amount of non-recyclable or non-recyclable plastic required to produce the container is considerably reduced, wherein at the same time, however, the highest tightness values are still ensured. The structure of the container should also be such that it can be manufactured with conventional, preferably linear packaging machines according to the preamble of claim 27 with as little conversion effort as possible without impairing the performance of these packaging machines. Another object of the invention is to provide a method for producing such a container that is as simple as possible and that fits seamlessly into the process sequence in standard packaging machines. Finally, it is a further object of the invention to provide a device for carrying out this method, with which the containers can be manufactured in high quality with the least possible expenditure on device technology.

The above-mentioned objects of the invention are achieved with regard to the creation of the container with the features of claim 1, with regard to the method by the method steps of claim 19 and with regard to the device for carrying out the method with the features of claim 27.

According to the invention, the soft film composite, which has a substantially lower surface rigidity than rigid films, is given its shape which stabilizes the container structure an erected cardboard blank, which is used in the shell-shaped, very thin-walled composite film so that it flatly stiffens the soft film composite. Because the cardboard blank is provided with a plastic coating on both sides, there is the advantage that the flat connection between the stiffening cardboard blank and the soft composite film made into a container can be made in a very short time, for example by a selective or area-covering thermal welding process. When using a cellulose or wood pulp shell, there is an intimate connection between the shell insert and the deep-drawn film in that the film or sealing layer flowing under the influence of heat can penetrate into the fibrous surface of the cellulose or wood pulp product, although there is good peelability , so that a separate disposal of carrier and sealing layer is possible. At the same time, the double-sided coating of the cardboard blank also ensures that box-like, spatially stable cardboard inserts can be produced with a high cycle frequency from, for example, strip-shaped but also other blanks - even with a continuous blank bottom, by thermally welding the overlapping fold sections. The processing of the cartons coated on both sides to form spatially stable container inserts with a spatially stable structure and circumferential wall collar can take place with such a high number of cycles that the production of the carton blanks is carried out in parallel with the processing of the soft composite film in a continuous deduction from a supply roll. The same applies to the use of cellulose or wood pulp trays, which are either stacked and separated in the pre-formed state in the packaging system or preformed in a separate work station. Since, according to the invention, the already folded, that is to say the erected and thus spatially stable, cardboard blank is preferably inserted into the molded depression of the soft film composite there are no problems with the positional alignment between the cardboard blank and the soft film composite. The folded, at least selectively thermofused cardboard blank, which has a spatially stable structure, can be handled like a tray insert with a relatively robust gripper device and accordingly positioned exactly over the depressions molded into the composite soft film. The risk of injuring the very thin-walled soft film composite when inserting the cardboard blank is reduced, especially if the edge areas of the tray insert or the erected cardboard blank have a chamfer surface that is at an obtuse angle to the adjacent wall surfaces. The measures according to the invention make it possible to work with a soft film composite system which only has a thickness in the range between 150 and 200 μm. In this way, the amount of plastic in the packaging that can no longer be reprocessed can be reduced to approximately 20% compared to conventional containers. If, for example, with a conventional polystyrene hard film with a thickness of 750 μm and a film width of 425 mm per 1000 m of film, 333 kg of non-reusable plastic were obtained, this proportion of plastic is reduced to approximately 70 kg by the measures according to the invention. The plastic coating of the cardboard blank can be made extremely thin-walled, for example with a thickness of about 12 microns, so that this packaging plastic waste is not significant. When using a cellulose or wood pulp bowl, this additional plastic content is completely eliminated.

The structure of the container according to the invention is completely sealed from the outside, regardless of the tightness of the shell insert or cardboard blank used, with a circumferential collar wall, in particular in the region of the corner edges. Of the The container according to the invention is therefore also suitable for packaging processes in which the interior of the packaging is evacuated and / or, if necessary, back-gassed after being filled with a stabilizing medium. The result is extremely high-quality packaging, with only a fraction of non-recyclable plastic. Suitable additives to the cellulose or ground wood pulp, which are then pressed into the shell inserts, can be used to take specific account of the food technology requirements, in particular the moisture resistance.

The construction of the container according to the invention benefits from the use of a very economical manufacturing process. If - according to a further development of the invention - the cardboard blank inserted into the molded trough of the composite film is obtained from a strip-like material, the opening on the base side, which is already stable in space, regularly results in an opening which can advantageously be used to to stabilize the preformed soft film composite from above by inserting the carton blank from above. The positioning accuracy of the cardboard blank in the preferably deep-drawn composite film can be additionally improved in this way and the risk of damage to the very thin-walled composite film is noticeably reduced.

The construction of the container according to the invention enables a manufacturing process that can be integrated seamlessly and without sacrificing performance in the process flow of commercially available packaging machines, as described at the beginning. The linear structure of such packaging systems can be maintained according to the invention. It is only necessary to complete the step of filling the container with the goods to be packaged to precede, in which the cardboard blank stiffening the composite soft film is inserted into the preformed, preferably deep-drawn shape. The device according to the invention for carrying out the manufacturing process for the more environmentally friendly food packaging can be obtained by simply retrofitting packaging systems already on the market. The throughput of the packaging system does not have to be reduced. It is only necessary to provide an additional device with which either spatially stable, i.e. erected and thermally welded cardboard blanks are inserted into the deep-drawn composite film, either in the form of tray inserts or cardboard boxes that have already been delivered, or in parallel by continuous processing of cardboard blanks cut into strips or otherwise pre-punched. The remaining components of the conventional packaging system can be kept unchanged.

The construction of the container according to the invention opens up the possibility of reducing the amount of cardboard required to form the container to a minimum, which is ensured, for example, by obtaining the erected cardboard insert from a strip-shaped blank. However, in order to provide additional protection against contamination for the packaging of moist or more fatty substrates or food, it is advantageous if the cardboard insert or the tray insert, which is coated on both sides, has a continuous bottom, from which the collar-like above circumferential side walls are angled. In this case there is no longer any risk that an uncoated cut edge of the carton comes into direct contact with the food to be packaged. This measure also effectively prevents the outer appearance of the packaging, for example in the area of the cardboard cut edge suffers from swelling due to moisture. This measure does not have to increase the weight of the packaging. This is because the cardboard can be made with less thickness due to the more stable structure that is supported across the bottom of the blank.

Preferably, the circumferential wall of the tray insert or the erected cardboard blank is designed so that the container opens slightly conically upwards. On the one hand, this measure simplifies the shaping process of the shell and it has the additional advantage that the outer composite film is subjected to as little mechanical stress as possible when the cardboard blank is inserted and when it is subsequently sealed.

Advantageous developments of the invention are the subject of the dependent claims. Advantageous embodiments of the container are outlined in claims 2 to 18, claims 20 to 26 further develop the manufacturing method according to the invention, and claims 28 to 42 protect advantageous developments of the device for carrying out the method.

A high-quality packaging results with the further development according to claim 4. Such soft film composite systems are available on the market with qualities that are optimally adapted to the application area in question. With a thickness of around 150 µm, these soft film composite systems are safe, i.e. Can be processed with little damage, even if deeper containers have to be formed.

The outer layer of the soft film composite system is preferably made of a polyamide plastic, a pretreated, for example corona-treated polyethylene plastic with a high melting point, a polyester plastic or a polypropylene system. The use of polyethylene for the outer layer brings additional price advantages. If a polypropylene system is used, the result is a composite that is completely recyclable without prior separation.

If the sealing layer of the container is formed according to claim 7, the non-easily recyclable soft film composite can be separated very easily from the rest of the container. Nonetheless, a very stable connection can be made via the sealing layer and the plastic coating of the cardboard blank, for example by using a thermal welding process, so that the mechanical stiffening of the flexible soft film composite by the cardboard is maintained over the long term.

According to the invention, the barrier layer is still formed by an ethylene-vinyl alcohol (EVOH or EVAL). However, since according to the invention the thickness of the plastic casing of the container is greatly reduced, the construction of the container according to the invention opens up the possibility of increasing the thickness of this ethylene-vinyl alcohol layer in relation to the overall thickness. This can improve the protective effect for the food without noticeably increasing the amount of non-recyclable plastic.

If the shell insert or cardboard blank completely lines the shell wall and has a bottom flange that is bent inwards, the cardboard blank insert for the deep-drawn soft film has a very stiffening effect. Nevertheless, the insert can even be made from very simply designed, strip-like cardboard blanks which are formed with individually selected folds or fold lines. The bottom flange, which is bent inwards, gives the carton insert a very good impression, even if the overlapped fold sections are only spot welded high torsional rigidity. Due to the flat connection of the cardboard insert with the outer wrapping made of the soft film composite, this torsional stiffness is transferred directly to the deep-drawn soft film composite, which is thus reliably protected against overstressing or overstretching even with heavy packaging. By choosing the cut of the cardboard box, the position and size of the opening on the bottom can be influenced in a targeted manner, which advantageously also takes place with regard to the goods to be packaged. For special substrates, a cardboard blank with a continuous bottom is preferably chosen, which then has an even higher load-bearing capacity. The structure of the cardboard blank according to claim 8 therefore has the particular advantage of giving the container sufficient stability with a minimum of cardboard consumption.

When using a strip-shaped cardboard blank, the width of the base flange is preferably selected so that it lies in the range between 10 and 40% of the container width.

For particularly heavy packaging, it is advantageous to develop the tray insert or the cardboard blank according to claim 10 and also to equip the top with a circumferential, outwardly angled edge flange. Because of the coating of the cardboard on both sides, this edge flange can also be produced from a strip-shaped blank by thermowelding of folded-over fold sections which overlap in the folded form. The resistance of the container to twisting is additionally improved in this way. In addition, the upper, peripheral flange offers protection for the edge of the deep-drawn soft film when inserting the cardboard blank. Finally, this measure ensures that even in the area of the upper container edge no uncoated cardboard cut edge comes into direct contact with the substrate to be packaged. It has shown that widths of a few mm support this effect reliably.

With a plastic coating of the cardboard blank according to claim 12, the cardboard insert can on the one hand be erected very easily and, on the other hand, in the erected form it can be economically produced to a warp-resistant structure, preferably thermowelded. The plastic coating according to claim 12 forms a connection with the sealing layer of the soft-film composite system that is as secure as it is quickly producible and that is long-term stable even at low temperatures. The container according to the invention is therefore particularly suitable for deep-freeze packaging. Nevertheless, after opening the container and after the packaged goods have been used up, the cardboard blank can be separated very easily from the flexible film composite system, which further improves the environmental compatibility of the container according to the invention.

Even with basis weights of about 200 to 300 g / m2, a very torsion-resistant container insert can be produced, which, in combination with the composite film surrounding this insert, creates a container that is in no way inferior to the conventional container made of thermoformed composite hard film.

The double-sided coating of the cardboard blank ensures that the food does not come into contact with the cardboard material itself. A recycling box, i.e. an inferior carton can be used.

The cardboard coating is also preferably made of a peelable plastic, so that the consumer is able in a few steps to recycle the recyclable Separate the components of the packaging from the non-recyclable components.

A particularly advantageous development of the method according to the invention for producing the food container is the subject of claim 19. With this development, the packaging system can be made very compact. Another advantage of this embodiment is that the negative mold for the production of the indentations in the soft film composite can simultaneously be used for positioning the soft foil composite with respect to the tray inserts or cardboard blanks to be used. This allows the working accuracy of the manufacturing process to be increased, and the risk of damaging the soft film composite system is already very small in that the shell insert is relatively smooth or smooth. the cardboard insert is plastic coated on both sides.

The method according to the invention of the flat stiffening of a soft film composite with a spatially stable, i.e. Rigid cardboard cutting can be carried out in various ways. For example, it is possible to feed the cardboard blank in strip form and to produce the spatial cardboard structure only in the already deep-drawn composite film. Advantageous, in particular with regard to the use of conventional packaging systems, is the further development of claim 20, according to which the cardboard blank is inserted into the plastic film in the form of a shell in the already folded state.

The development of the method according to claim 24 leads to particularly stable containers. The interlocking between the shell insert or cardboard blank and the plastic composite film leads to an even higher stability of the container and to an even better stiffening together with the soft film composite, which is not inherently stable on the surface. Furthermore This type of design of the side walls has advantages when flushing the filling material with gas.

If the molded trough of the plastic film is stabilized by an air flow during the insertion of the cardboard blank, incorrect controls can be reliably ruled out, even with very thin-walled soft film composite systems. However, this stabilizing air flow is advantageously combined with a suction flow which is applied from the counterform to the outside of the soft film composite.

The device for carrying out the method can be implemented with conventional components of standard packaging systems. A closer look at the developments of the device according to claims 28 to 42 is therefore not necessary at this point. These further developments aim in particular to protect the soft film composite as effectively as possible during transport through the packaging system and to keep the clock frequency of the device high. The device according to the invention is also suitable for the production of several containers in one work step and in one work station, which is the subject of claim 37.

With the development of the device according to claims 43 to 45, there is the particular advantage of an extremely simple and space-saving integration of the film, deep-drawing and tray or cardboard blank insertion station in conventional packaging systems or lines. The packaging system can be operated unchanged in the same cycle, and there is no need to extend the film throughput. The modular design makes it easy to convert the system to process a wide variety of container shapes.

Further advantageous embodiments are the subject of the remaining subclaims.

Fig. 1

eine schematische Draufsicht einer Anlage für die Herstellung eines erfindungsgemäßen Lebensmittelbehälters;

Fig. 2

eine schematische Schnittansicht gemäß II-II in Figur 1;

Fig. 3

eine schematische Schnittansicht gemäß III-III in Figur 1;

Fig. 4

die Ansicht gemäß IV in Figur 3;

Fig. 5

die Einzelheit "V" in Figur 6;

Fig. 6

eine schematische Schnittansicht gemäß VI-VI in Figur 1 mit einer etwas modifizierten Formgebung des eingesetzten Kartonzuschnitts;

Fig. 7

in vergrößertem Maßstab einen Schnitt gemäß VII-VII in Figur 1;

Fig. 8

den Schnitt gemäß VIII-VIII in Figur 6 - 90° gedreht - im Bereich einer Seitenwand, die mit einer Einrichtung zur Ausbildung von versteifenden Sicken ausgestattet ist;

Fig. 9

eine perspektivische Ansicht der unteren Werkzeughälfte zur Aufnahme des Kartonzuschnitts;

Fig. 10

in vergrößertem Maßstab eine Teil-Schnittansicht des versiegelten Behälters im Bereich des oberen Randflansches;

Fig. 11

eine perspektivische Ansicht der mit der Unterform gemäß Figur 9 korrespondierenden Oberform;

Fig. 12

eine erste Ausführungsform eines Kartonzuschnitts im ungefalteten Zustand;

Fig. 13

eine weitere Ausführungsform eines Kartonzuschnitts im ungefalteten Zustand;

Fig. 14

eine perspektivische Ansicht einer Eckkante des aus dem Zuschnitt gemäß Figur 13 gefalteten Karton-Einsatzes;

Fig. 15

eine Seitenansicht einer Anlage zur Durchführung des erfindungsgemäßen Verfahrens zur Herstellung eines Behälters;

Fig. 16

eine Draufsicht einer weiteren Ausführungsform eines Kartonzuschnitts im Zustand vor dem Aufrichten;

Fig. 17

eine perspektivische Ansicht des Kartonzuschnitts im aufgerichteten Zustand;

Fig. 18

eine Einzelheit der Ansicht gemäß Figur 17 im Bereich einer Seitenkante;

Fig. 19

eine schematische Schnittdarstellung im Bereich der Form- und Arbeitsstation gemäß einer weiteren Variante; und

Fig. 20

eine Draufsicht der Verpackungsanlage gemäß Figur 19.

Several exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:

Fig. 1

a schematic plan view of a plant for the production of a food container according to the invention;

Fig. 2

a schematic sectional view according to II-II in Figure 1;

Fig. 3

a schematic sectional view according to III-III in Figure 1;

Fig. 4

the view according to IV in Figure 3;

Fig. 5

the detail "V" in Figure 6;

Fig. 6

a schematic sectional view according to VI-VI in Figure 1 with a slightly modified shape of the cardboard blank used;

Fig. 7

on an enlarged scale a section according to VII-VII in Figure 1;

Fig. 8

the section according to VIII-VIII in Figure 6 - rotated 90 ° - in the region of a side wall, which is equipped with a device for forming stiffening beads;

Fig. 9

a perspective view of the lower half of the tool for receiving the cardboard blank;

Fig. 10

on an enlarged scale, a partial sectional view of the sealed container in the region of the upper edge flange;

Fig. 11

a perspective view of the upper mold corresponding to the lower mold according to FIG. 9;

Fig. 12

a first embodiment of a cardboard blank in the unfolded state;

Fig. 13

a further embodiment of a cardboard blank in the unfolded state;

Fig. 14

a perspective view of a corner edge of the cardboard insert folded from the blank according to Figure 13;

Fig. 15

a side view of a plant for performing the method according to the invention for producing a container;

Fig. 16

a plan view of another embodiment of a cardboard blank in the state before erection;

Fig. 17

a perspective view of the carton blank in the erected state;

Fig. 18

a detail of the view of Figure 17 in the region of a side edge;

Fig. 19

a schematic sectional view in the area of the molding and work station according to another variant; and

Fig. 20

a plan view of the packaging system according to Figure 19.

In FIG. 1, the reference numeral 20 denotes a composite film wound on a roller, as it is offered on the market by the company "WALKI" in various versions with different protective properties. This composite film is a soft film composite, for example with the following structure:

The outer layer forming a mechanical protective shield is formed, for example, from a polyamide, a pretreated, preferably corona-treated polyethylene, preferably with a high melting point, or a polyester plastic. The thickness of this layer is, for example, 30 microns. This mechanical protective layer is followed by a barrier layer made of ethylene vinyl alcohol (EVOH or EVAL), which is effective for oxygen and carbon dioxide. The upper layer facing in the illustration according to FIG. 1 is formed by a sealing layer which is preferably formed by a peelable or peelable polyethylene plastic or plastic system. The term "soft film composite" is to be understood in the following to mean a composite film which is flexible, i.e. is not inherently stable. The wall thickness of this soft film composite is preferably in the range between 150 and 200 μm, the EVAL barrier layer having a thickness in the range between 4 and 30 μm and the sealing layer in the range between 50 and 100 μm.

The composite film 20 is drawn off, for example, in a width of approximately 400 to 500 mm from a roller 22 and fed to the linearly structured packaging system, which largely includes work stations, such as those realized in conventional packaging machines, for example from the "Multivac" company are. The main stations of the packaging machine are described in more detail below:

30 denotes a deep-drawing station, in which the composite film 20 preheated by means of a heating device 32 is negatively deformed in the deep-drawing process. For this purpose, a negative mold tool 34 which can be moved back and forth in the vertical direction (arrow B) is provided, in which four negative molds 36 are formed. The negative molding tool 34 is therefore suitable for the simultaneous production of four deep-drawing operations. However, it should be emphasized at this point that the invention is not limited to the special arrangement and shape of the containers shown. Rather, any type of packaging and also of packaging groups can be produced by replacing the negative molding tool 34 in the area of the deep-drawing station 30 without departing from the basic concept of the invention.

Each negative mold 36 is connected via a line duct system 38 to a negative pressure connection 40, so that a vacuum can be generated in a time-controlled manner below the composite film 20 drawn over the negative molds 36, with which the composite film can be brought into the form shown in FIG represents later, finished food container. As can be seen from FIG. 1, four indentations are introduced into the composite film 20 per tool stroke. The indentations are identified in FIG. 1 by reference number 42.

From the thermoforming station 30, the composite film or the soft film composite runs intermittently by means of a transport chain to a work station 50, in which - preferably in one operation - a corresponding number of torsionally rigid cardboard blanks 52 are inserted into the group of four of the indentations 42. The composite film In the area of this workstation, 20 is still connected over the entire surface, which can best be seen from the illustration according to FIG. 3. The thin soft film composite 20 is not - emphasized in the illustration according to FIG. 3 - supported between the individual indentations by a guide rail. The exact positioning of the indentations 42 in the work station 50 is carried out with the aid of a lower tool part 54, which is guided to be movable in the vertical direction via columns 58 and has inner recesses 56 which form the negative for the final shape of the packaging to be produced. Specifically, the depth T of the inner recess 56 is equal to the dimension V of the indentation 42. The remaining contour of the inner recess 56 also corresponds to the shape of the indentation 42, so that when the lower tool 54 is moved upward, there is a flat, full contact of the composite film 20 on the lower tool 54. The reference numeral 60 shows a transport and shaping stamp, referred to below as the transport plate, which is also mounted such that it can move in the vertical direction and is held on a swivel arm 62 with a swivel axis 64. The transport plate. 60 has a number of projections in the form of positive molds 66 corresponding to the number of inner recesses 56 below, with which cardboard blanks which are to be described in more detail below and are brought into a box-like shape can be transported from a folding station 70 to the workstation 50 and can be inserted into the indentations 42.

The cardboard blanks 52 (see FIG. 3) are obtained from a cardboard coated on both sides, which is wound on a cardboard roll 72. In the embodiment of the container manufacturing, filling and sealing system shown in FIG. 1, the production of the cardboard blanks 52 takes place synchronously and in time with the processing of the soft film composite 20. 74 is a cutting device with which the cardboard web 76 in strips 76-1 to 76-4 is divided. The number of strips corresponds to the Number of containers to be processed simultaneously in one work step. The strips 76-1 to 76-4 subsequently run into a folding device 78, in which the individual strips are provided with such a cut and folding lines 80 that a cup-like cardboard insert 52 is produced from a single strip in a cardboard folding device 82 , which is held in position by the individual positive molds 66 on the transport plate 60. In Figure 1, the cardboard inserts 52 located on the underside of the transport plate 60 are only indicated with dashed lines, only two such cardboard inserts being shown for reasons of simplification.

The transport plate 60 is preceded by a device 84 in which individual strips 86-1 to 86-4 which have been cut to length are erected in a box shape and are firmly connected to one another in the region of the overlapping fold sections, preferably thermowelded, so that spatially stable at the exit of the device 84 , torsion-resistant cardboard cut inserts 52 are present, which can be gripped by means of the transport plate 60 and positioned precisely by means of a clocked, cyclical pivoting movement, which is indicated in FIG. 1 by the arrow S, over the inner recesses 56 of the lower tool 54 of the work station. Instead of the continuous production of the cardboard cardboard inserts, it is also possible to feed these inserts to the system in batch mode and to feed them "just in time" to the workstation 50 using the transport plate 60.

In order to simplify the manufacture of the cardboard insert and also with regard to the subsequent further processing of the insert, the cardboard 76 is provided on both sides with a plastic coating which consists of a thermally weldable polyethylene plastic (PE). The thickness of this plastic coating is, for example, in the range between 10 and 15 µm and the arrangement is preferably such that the coating is easily peelable, ie peelable. The core material of the coated cardboard 76 consists of so-called recycled cardboard and a basis weight in the range between 200 and 300 g / m2 is preferably selected for the cardboard blank. In the erected and at least spot-welded state of the folded and folded cardboard strip 86-1 to 86-4, the insert can best be transported over the wall sections 88. The folding of the cardboard strips 86 takes place in coordination with the shape of the positive mold 66 in such a way that the cardboard insert 52 surrounds the positive mold 66 in a form-fitting manner. The height H of the cardboard insert essentially corresponds to the dimension V of the indentation 42 or the depth T of the inner recess 56 in the lower mold 54.

In order to secure the cardboard inserts 52 against falling during the transport into the position according to FIG. 3, a large number of strip-like or rib-shaped pistons 90 arranged in rows are slidably slidably received in the side wall of the positive mold 66. The control spaces 92 lying behind these strip-shaped or rib-shaped pistons 90 are connected to a channel system 94. If the control spaces 92 are pressurized in a timed manner via the channel system 94, the rib-shaped pistons 90 can extend slightly beyond the wall 98 against the force of return springs 96 and come into frictional engagement with the inner surface of the walls 88 of the erected carton 52. This state the strip-shaped piston 90 is indicated in FIG. 11 on the side wall 98 facing the viewer, while the rib-shaped pistons 90 are shown in the retracted position in the adjacent side wall.

It has already been described above that the cardboard inserts are formed from strips 86-1 to 86-4. Im erected and the torsionally rigid, preferably thermowelded state of the folded strip, in the simplest embodiment a structure is formed with a circumferential collar formed by the wall sections 88 and an open floor 100 which is essentially at right angles thereto and which is formed by floor flanges 102 which are bent inwards. The width B102 of these flanges is an adjustable fraction of the total width W of the container.

Because of the perforated bottom 100, there is the possibility of supporting the latter via the transport plate 60 when inserting the carton 52 into the indentations 42. For this purpose, a compressed air duct system 104 is provided in the transport plate 60 and the associated holder, with which an air flow indicated by the arrows 106 can be generated in a time-controlled manner. The air flow emerges from the bottom end face of the positive molds 66 and is directed into the interior of the indentations 42, so that when the lower tool 54 is moved upwards, the full contact of the deep-drawn composite film 20 on the inner wall of the recess 56 is promoted. The compressed air duct system 104 can also be used to control the stroke movement of the rib-shaped pistons 90.

The representations according to FIGS. 1 and 3 differ from one another insofar as the cardboard insert according to FIG. 1 is not only equipped with a bottom flange 102 but also with an upper edge flange 108 with an optional width B108. However, this top edge flange 108 is only beneficial if particularly heavy packaging is to be produced. Figure 4 shows this top flange 108 particularly clearly. Hatched areas 110 are indicated where folded fold sections of the cardboard blank overlap in the erected form. In these areas, there is preferably a flat or selective thermal welding instead of. Since the cardboard is coated on both sides, a firm connection of these overlapping areas can be ensured regardless of the folding method.

FIG. 6 shows the position assignment between the lower tool 54 and the transport plate 60 as the upper tool shortly before the bottom dead center of the transport plate 60 is reached. The lower tool 54 has already reached the top dead center. The cardboard insert 52 lies together with the composite film 20 snugly against the inner contour 56 of the lower tool 54. The positive molds 66 of the transport plate 60 are positively immersed in the indentations. The cardboard insert 52 is thereby pressed flat against the composite film 20 both in the area of the wall sections 88 and in the area of the bottom flange 102 and - if present - also in the area of the upper edge flange 108. When pressing together, the upper flange 108 which may be present - see FIG. 10 - can be compressed somewhat, so that the thickness D108 becomes smaller than the wall thickness D52. The composite film 20 is not overstressed, since it in turn is supported flatly on the surface contour of the lower tool 54. In the closed state of the tool parts 54, 60, a heating device, designated 112, is actuated, so that in the area of the contact sections between the cardboard insert 52 and the composite film, spot or area welding occurs at the points 118. This welding covers the entire contact area between the cardboard insert 52 and the film 20. The cardboard insert thus stiffens the flexible, i.e. flaccid soft film over a large area, so that the dimensional stability of the cardboard insert 52 is completely transferred to the soft film composite 20.

In particular, when particularly stable containers have to be produced, the inner recesses 56 in the lower tool part 54 are designed in the way that this is the case in detail 9 can be removed. In this case, a series of elongated depressions 116 are formed in wall surfaces 114, which, when the positive molds 66 are completely retracted, lie flush with the strip-shaped pistons 90. This state can be seen in the section according to FIG. 8.

Preferably, when the heating devices 112 are activated, the duct system 94 is pressurized with compressed air so that the rib-shaped or strip-shaped pistons 90 perform a full stroke outwards and the carton 52 together with the outer skin from the soft film composite 20 into the Depress recesses 116 against the force of the return springs 96. In this way, an essentially vertically corrugated profile of the side walls of the container is created, which leads to an increase in the stability of the container. When the control pressure in the duct system 94 is reduced, the springs 96 push the pistons 90 in question again. However, the beaded shape of the side walls is retained and also contributes to an improvement in the areal connection between the cardboard insert 52 and the soft film composite 20.

FIG. 5 shows an enlarged representation of a section of the container immediately after the connection between the cardboard insert 52 and the soft film composite 20 has been completed. This representation shows the multilayer structure of both the coated cardboard and the soft film composite. 52-1 denotes the core area made from recycled cardboard. The coating films made of thermally weldable polyethylene (PE), which have a thickness of approximately 10 to 15 μm, are indicated by 52-2. 118 denote those locations at which a thermal seal is produced between the coating film 52-2 and a sealing layer 20-3 of the soft film composite 20. The sealing layer preferably consists of peelable, ie peelable polyethylene (PE plastic). 20-2 denotes the oxygen and CO2 barrier layer made of ethylene vinyl alcohol (EVAL) and 20-1 the mechanical protection outer layer, which is formed either from a polyamide, a pretreated, preferably corona-treated high-melting point polyethylene or a polyester plastic is.

The indentations 42 braced in this way finally leave the work station 50 and are fed to a food loading station 120 and then to a sealing station 130. The filling station 120 is not shown in the illustration according to FIG. 1, since this station does not differ from conventional filling stations. A conventional composite cover film 132 runs into the system in the sealing station 130. The cover film 132 is continuously pulled off a roll 134 and fed via deflection rolls 136, 138. The sealing station 130 also has a lower support tool 140, which interacts with a sealing plate 142. The sealing plate 142 can be moved upwards and downwards and is partially heated in order to bring about a thermal welding between the cover film 132 and the sealing layer 20-3 of the soft film composite 20 at the hatched areas VS in FIG. 1.

Figure 10 shows the condition of the container after sealing. This figure shows that the cover film 132, when the top edge flange 108 is present, nestles closely around it and is thermally welded to the soft film composite 20 in the area VS. FIG. 10 shows that the cover film 132 is also designed as a composite film, a sealing layer 132-3 coming to lie opposite the sealing layer 20-3. 132-2 denotes an oxygen and / or CO2 barrier layer made of ethylene vinyl alcohol (EVAL). The inside of the packaging is therefore surrounded on all sides by a composite film with a barrier layer.

FIG. 7 shows in detail how the sealing plate 142 must be designed in order to be able to seal the container in the manner according to the invention. In the event that the cardboard insert has an upper edge flange 108, the sealing plate has correspondingly designed depressions 144, between which flat webs 146 remain which coincide with the sealing areas VS. In the area of these flat webs 146, partial heating devices 148 are provided, which can also extend into the area of the top edge flanges 108. Additional devices, such as, for example, are not shown in the illustrations. B. an evacuation device or a return gas device. However, it should be emphasized at this point that these devices can of course be used with the plant according to the invention for the production and filling of the food containers.

After passing through the sealing station 130, the individual containers are connected via the cover film 132 and the still connected soft film composite 20. The filled and sealed containers then pass into a cutting device 150. In this device 150, the containers are cut along lines that lie in the sealing areas VS. Such a parting plane is designated by a dash-dotted line in FIG. 10 with 152. The cutting device 150 preferably has a longitudinal cutting knife 154 and a transverse cutting knife 156. The containers 158 separated behind the cutting device 150 can then be removed and suitably packed.

Finally, advantageous cuts with corresponding folds for the cardboard coated on both sides are to be described with reference to FIGS. 12 to 14. FIG. 12 shows a cut cardboard strip with which a cardboard insert according to FIG. 4 can be produced. With dashed lines the fold lines are marked. The hatched areas represent the overlap areas in which the surfaces that overlap are thermally welded in order to produce a torsionally rigid spatial structure.

An embodiment of the cardboard strip cut, with which an edge flange 108 ′ running around the top side can be produced, is shown in FIGS. 13, 14. The thick lines represent the margins of the cut or cut lines. The thin lines are fold lines. The blank according to FIG. 13 is folded in the area of the corners, as can be seen in the perspective illustration according to FIG. 14. In the erected state, the fold lines 160, 162 come into contact with one another. The intermediate folding line 164 delimits an outwardly folded flap, which is preferably pivoted into a wall plane of the erected insert and is heat-welded to this surface. The edge flanges 108 'overlap in the area Ü and are also thermowelded there.

FIG. 15 shows an overview again of a side view of the plant according to the invention for producing a food packaging. Those stations in the system that correspond to the previously described work stations are identified by identical reference numerals. In this overall view, a filling station designated 120 can be seen going beyond the representation according to FIG. The feed point of the cover film 132 can also be seen in detail. The illustration according to FIG. 15 shows that the system according to the invention for producing the containers differs from a conventional packaging system only with regard to workstation 50. The other stations 30, 120, 140 and 150 can be taken over by a conventional system in identical training, if necessary with minor reconstructions.

The concept of container production according to the invention even allows stations 30 and 50 to be combined to form a unit Z, which results in a very compact system.

FIGS. 16 to 18 show further embodiments of the invention, namely further configurations of the cardboard blank which stiffens the shell and is coated on both sides with plastic. Figure 16 is a schematic plan view of an embodiment of the carton blank in the unfolded state. In Figure 16, only one half of the cardboard blank is shown. The axis of symmetry of the carton blank designated 252 is designated 254. The thin lines in FIG. 16 represent fold lines 280, which are preferably pre-embossed to allow the cardboard blank to be erected either in a separate work station or in the deep-drawn composite film in a short time.

Figure 17 shows the cardboard blank in the erected state. In contrast to the embodiments described above, no upper edge flange sections adjoin the side walls 250. In another difference, the cardboard blank 252 is not formed by a cardboard strip, but by a flat structure, so that a container with a continuous bottom wall 256 is formed after erection. This makes the container more dimensionally stable, so that the wall thickness of the carton can be reduced further. In addition, this design has the advantage that no uncoated area of the cardboard blank is directly exposed to the substrate to be packaged. The use of a cardboard blank according to FIGS. 16 and 17 is therefore particularly appropriate when substrates that are moist or have a higher fat content are to be packed without contamination. Overlap areas of the folded wall sections are designated by 210. In these Areas are preferably punctiform or flat thermowelding, which can be achieved with simple measures due to the double-sided coating of the cardboard blank.

Finally, the cardboard blank according to FIGS. 16 and 17 is designed in such a way that sharp edges are avoided in the erected state. Chamfer surfaces 258 are formed in the area of the corner edges, which are at an obtuse angle to the adjacent side surfaces 250. In this way, the risk of damage to the thin-walled, deep-drawn composite film is effectively countered when inserting the cardboard blank 252.

Figure 17 also shows that the cardboard blank is selected so that the cardboard blank opens up slightly. In other words, the side walls 250 are slightly tapered upwards. This measure also effectively counteracts overstressing of the thin-walled, deep-drawn composite film either when inserting the cardboard blank and / or during the final sealing process.

Reference number 260 denotes a further fold line which gives the side walls 250 a locally limited flexibility in the region of the bottom edge, so that overstretching of the thermoformed composite film can also be excluded in this region.

The cardboard blank according to FIGS. 16 and 17 can be handled in the same way and inserted into the deep-drawn composite film trough, as has been described with reference to the exemplary embodiments described above. This method is therefore no longer to be described in connection with this embodiment.

According to an alternative embodiment, the cardboard blank according to FIGS. 16 and 17 can be provided with a cut-out 262 indicated by dash-dot lines. The cutting edge which arises at the edge of the punched out can be thermally sealed during the punching process, so that even in this case the inserted substrate cannot come into direct contact with the cardboard, which as a rule absorbs water.

A further embodiment of a cardboard blank 352 is indicated in FIG. The peculiarity of this cardboard blank is that the lower corner edges are flattened or blunted. Accordingly, an upper chamfer surface 358 adjoins a lower chamfer surface 368. With this configuration, the insertion of the cardboard blank 352 is further simplified, the risk of damage to the thermoformed composite film being able to be further reduced even under thermal stress.

FIGS. 19 and 20 show a particularly advantageous embodiment of the device for producing the container according to the invention. With this device, it is possible to integrate the units for deep-drawing the soft film and for inserting the stiffening shell into a conventional hard film packaging system in a space-saving manner and with a minimum of conversion work. Those components which are functionally comparable to components of versions already described are provided with similar reference numerals in FIGS. 19 and 20, which is increased by "400".

The soft film 420 runs into the molding station, ie into the deep-drawing station 430, and is heated there by means of a heating plate 432, which is located above a modular molding insert 434. The thermoforming station is immediately adjacent the work station, ie the tray insertion station 450, which in turn has a modular insert 454. Both modules 434 and 454 preferably have a common carrier, via which a synchronous lifting movement is initiated. The common carrier can be taken over from the conventional hard film packaging system without reconstructions.

A transport and fixing stamp 460 for the trays or cardboard blanks 452 to be inserted cooperates with the module 454 after the module has completed its HSP working stroke and the stamp 460 has been inserted into the mold.

If the packaging form is to be changed, it is only necessary to replace the modules 434 and 454 and the head of the stamp 460.

FIG. 20 shows that the transport and fixing stamp 460 has to perform a simple pivoting movement by only 90 ° in order to transport the shell inserts into the mold. This keeps the number of cycles high. Of course, other kinematic devices can also be used.

Figures 19 and 20 represent the conditions only schematically. Of course, it is advantageous to design the modules 434 and 454 in such a way that the bridge sections B1 and B2 become the same size, which is indicated in FIG. 20.

The film runs from the work station 450 with deep-drawn drawings and inserted shell inserts to a sealing and sealing station 530, in which the upper film 532 fed in via a deflection roller 538 runs in, as indicated in FIG. 15.

Of course, deviations from the invention described above are possible without departing from the basic idea of the invention. For example, it is also possible to additionally work with positive molds in the area of the deep-drawing station 30 if particularly deep containers are to be produced. These positive forms can then be used to pre-deform the soft film composite 20 before the deep-drawing process in order to rule out extreme film stretching.

It is also not necessary to design the cardboard blank on the top with an edge flange - all the way around or not. In this case, the sealing station is simplified because the sealing plate can have a simpler shape. If a top-side, angled edge flange of the cardboard blank or insert is not provided, the design of the heating devices is also simplified since they then no longer have to cover the area covered by the edge flange.

Finally, the device can also be modified so that the feed device for the erected carton inserts is separate from the top mold in the work station, i.e. from the form stamp.

The invention has been described above using exemplary embodiments in which a cardboard blank is inserted into the deep-drawn shell. The object described at the outset is also achieved if a shell insert in the form of a cellulose or ground wood shell with an otherwise comparable geometry is used.

The construction of the container described above results in a food packaging which, as can best be seen in FIG. 10, forms an oxygen and CO2-impermeable envelope on all sides. The manufacturing process kept as simple as possible, whereby conventional packaging systems can be used with the same clock frequency and with the least possible conversion effort.

The invention thus creates a container for the packaging of foodstuffs, with a thermoformed shell made of plastic and a cover in the form of a plastic composite film that is welded around the top via a flange section. In order to improve the environmental friendliness of the packaging while at the same time simplifying production using conventional packaging machines, the shell (42) is formed by a thin-walled, non-area-stable soft-film composite system (20) and on the inside at least in the region of the shell wall, which preferably has a slightly conical upward direction opens, either by means of a dimensionally stable shell insert containing cellulose or wood pulp or by a cardboard blank (52) which is plastic-coated on two sides and welded to the shell (42) at least at discrete points (118).

Claims (45)

1. A receptacle for packaging food, comprising a deep-drawn bowl having a thin-walled plastic soft foil system, which is not surface-stable in itself, and a cover welded therewith circumferentially on the upper side via a flange portion in the form of a plastic compound foil, characterized in that the soft foil system is a soft foil compound system which is fully stiffened at the inside in the area of the bowl wall, which preferably opens slightly conically toward the top, by

   a) a dimensionally stable bowl insert containing cellulose or wood pulp

   or

   b) a cardboard blank (52) plastic-laminated on both sides and welded with the bowl (42) at least at discrete points (118), which cardboard blank is obtained from a blank (81-1 to 86-4; 152; 352) having a folding (80; 260; 280) adapted to the inner contour of the bowl (42) and has a spatially stable structure due to the welding of selected folding sections (110; Ü; 210) overlapping in the final folded shape,

   wherein the stiffening comprises at least a partial area of the bottom of the bowl.
2. A receptacle according to claim 1, characterized in that the cardboard blank (52) is obtained from a strip-shaped blank (81-1 to 86-4) to which a spatially stable, collar-like structure has been imparted by the welding of selected folding sections (110; Ü; 210) overlapping in the final folded shape.
3. A receptacle according to claim 1, characterized in that the cardboard blank (252) or the bowl insert has a one-piece bottom (256).
4. A receptacle according to any one of the claims 1 to 3, characterized in that the soft-foil compound system (20) of the bowl (42) is constituted by a multi-layer compound foil (20) having an outer layer (20-1) capable of bearing mechanical load, an oxygen and CO2 barrier layer (20-2) positioned in the central portion and an inner sealing layer (20-3).
5. A receptacle according to claim 4, characterized in that the outer layer (20-1) is constituted by a PA synthetic, a pretreated, for example corona-treated polyethylene (PE) synthetic having a high melting point, a polyester synthetic or a polypropelene synthetic material.
6. A receptacle according to claim 4 or 5, characterized in that the barrier layer (20-2) is constituted by an ethylene vinyl alcohol (EVOH).
7. A receptacle according to any one of the claims 4 to 6, characterized in that the sealing layer (20-3) is constituted by a preferably peelable polyethylene (PE) synthetic material.
8. A receptacle according to any one of the claims 2 to 7, characterized in that the cardboard blank (52) or the bowl insert completely lines the bowl wall (42-1) and includes an inwardly bent bottom flange (102).
9. A receptacle according to claim 8, characterized in that the bottom flange (102) has a width (B102) which is between 5 and 40% of the width (W) of the receptacle.
10. A receptacle according to any one of the claims 1 to 9, characterized in that the cardboard blank (52) or the bowl insert has a circumferential outwardly bent edge flange (108; 108') at the upper side.
11. A receptacle according to claim 10, characterized in that the edge flange (108; 108') has a width (B108) of between 2 and 10 mm, preferably of 5 mm.
12. A receptacle according to any one of the claims 1 to 11, characterized in that the plastic coating (52-2) of the cardboard blank (52) is formed of a thermally weldable polyethylene (PE) synthetic material.
13. A receptacle according to any one of the claims 1 to 12, characterized in that the soft foil (20) has a thickness (D20) ranging from 150 to 200 um.
14. A receptacle according to any one of the claims 1 to 13, characterized in that the cardboard blank (52; 252; 352) or the bowl insert has a gsm substance ranging from 200 to 300 g/m2.
15. A receptacle according to any one of the claims 1 to 14, characterized in that the plastic coating (52-2) of the cardboard blank (52) has a thickness (D20) ranging from approximately 10 to 15 um.
16. A receptacle according to any one of the claims 1 to 15, characterized in that the cardboard blank (52; 252; 352) comprises a cardboard obtained from recycled waste products as base material (52-1).
17. A receptacle according to any one of the claims 1 to 16, characterized in that the plastic coating (52-2) of the cardboard blank (52; 252; 352) is constituted by a synthetic material, preferably on the basis of polyethylene without any residues, which can be stripped off the adjacent stiffening.
18. A receptacle according to any one of the claims 1 to 17, characterized in that additives such as, e.g., zirconium acetate, are added to the fiber mass of the bowl insert so as to improve the moisture stability.
19. A method of manufacturing a food receptacle in which a plastic foil is brought into bowl shape in a shaping means and the bowl is filled with food and then circumferentially connected gas-tight with an upper flange of the bowl, characterized in that,

    a) prior to filling, an insert stiffening the plastic foil (20) at least in the area of the walls (42-1) and in the transition region to the bottom of the bowl (42-2) is inserted into the bowl (42) which consists of a deep-drawn thin-walled plastic soft foil system, the insert being either a dimensionally stable bowl insert containing cellulose or wood pulp or a cardboard blank (52; 252; 352) plastic-laminated on both sides, and

    b) the inserted bowl insert or cardboard blank (52; 252; 352) is fixedly connected, preferably thermally supported and welded, with the plastic foil (20) in selected areas (118) so that the stiffening covers the wall and at least a partial area of the bottom of the bowl.
20. A method according to claim 19, characterized in that the bowl insert or the cardboard blank (52; 252; 352), resp., is inserted and is connected with the plastic foil (20) at the same working position (50), the bowl insert or the cardboard blank (52; 252; 352) being inserted into the plastic foil (42) brought into bowl shape preferably in the pre-formed or folded, i.e. erected state.
21. A method according to claim 20, characterized in that the cardboard blank (52; 252; 352) is formed of a blank (86-1 to 86-4; 252; 352) which has a folding corresponding to the inner contour of the plastic foil (42) brought into bowl shape and to which a spatially stable structure has been imparted after folding by the connection, particularly the welding of selected folding portions (110; Ü; 210) overlapping in the final folded shape.
22. A method according to claim 20, characterized in that the cardboard blank is formed of a strip-shaped blank (86-1 to 86-4) which has a folding corresponding to the inner contour of the plastic foil (42) brought into bowl shape and to which a spatially stable, collar-like structure having open cutouts in the bottom surface has been imparted after folding by the connection, particularly the welding of selected folding portions (110; Ü) overlapping in the final folded shape.
23. A method according to claim 21 or 22, characterized in that the cardboard blank (52; 252; 352) is inserted into the plastic foil (42) brought into bowl shape, after the selected folding portions (110; Ü; 210) overlapping in the folded shape have been fixedly connected to each other.
24. A method according to any one of the claims 18 to 23, characterized in that the bowl insert or the cardboard blank (52; 252; 352), resp., is indented with the opposite wall of the plastic foil (20) brought into bowl shape at least in the area of the side walls (42-1).
25. A method according to any one of the claims 18 to 24, characterized in that the trough (42) of the plastic foil (20) brought into bowl shape is stabilized by an airflow (106) during insertion of the bowl insert or the cardboard blank (52; 252; 352), respectively.
26. A method according to claim 25, characterized in that the air flow (106) is directed through a bottom-side orifice (100) of the bowl insert or the cardboard blank (52) obtained and erected from a strip-shaped cardboard into the inside of the deep-drawn trough (42).
27. An apparatus for manufacturing a food receptacle, comprising a shaping station for forming a trough in a plastic foil fed to the shaping station (30) and a sealing station (140) connected to a food filling station (120), characterized in that a working station (50) is disposed ahead of the food filling station (120), in which working station a bowl insert stiffening the plastic foil (20) at least in the area of the walls (42-1) and in the transition region to the bottom of the bowl (42-2) or a cardboard blank (52; 252; 352) plastic-laminated on both sides is inserted into the bowl (42) prior to filling, and in that the inserted bowl insert or cardboard blank (52), resp., is fixedly connected, preferably connected with the aid of heat, such as e.g. thermally welded, in selected portions (118) so that the stiffening covers at least the wall and a partial area of the bottom of the bowl.
28. An apparatus according to claim 27, characterized in that the working station (50) includes a lower negative mould (54) receiving the trough-shaped plastic foil (42, 20) with form-fit and an upper positive mould (66) which thereupon can be brought into an aligning opposed position, wherein the bowl insert or the cardboard blank (52; 252; 352), resp., is adapted to be pressed in the closed state of the mould fully against the plastic foil (42; 20) and to be fixedly connected therewith by an at least partial heating (112) of the negative mould (54).
29. An apparatus according to claim 27 or 28, characterized in that in the upper positive mould (66) a channel system (104) is formed through which, during approximation to the negative mould (54), a fluid stream (106) stabilizing the trough-like formed plastic foil (42) can be directed to the plastic foil (42).
30. An apparatus according to any one of the claims 27 to 29, characterized in that the two mould halves (66, 54) of the working station (50) are vertically movable.
31. An apparatus according to any one of the claims 27 to 30, characterized in that the positive mould (66) is designed as a transport means (60, 62) for the bowl insert or the cardboard blank (52), respectively.
32. An apparatus according to claim 31, characterized in that the transport means (60, 62) can be reciprocated between the working station (50) and a folding station (70) in which the cardboard blank (52; 252; 352) is erected.
33. An apparatus according to claim 32, characterized in that the folding station (70) includes a heating means (84) for welding folding portions (110; Ü; 210) which overlap in the folded and erected final form.
34. An apparatus according to any one of the claims 31 to 33, characterized in that in the area of the side faces (98) opposing the trough wall (42-1) the positive mould (66) receives a number of substantially ribbed plungers (90) which extend at a parallel distance from each other substantially vertically to the horizontal edges of the positive mould (66) and can be brought from an embedded position into a protruding position by actuating a pressure fluid.
35. An apparatus according to claim 34, characterized in that in the closed state of the mould consisting of the positive mould (66) and the negative mould (54) the ribbed plungers (90) are positioned opposite to corresponding recesses (116) in the side walls of the negative mould (54) into which the bowl insert or the cardboard blank (52; 252; 352), resp., can be formed together with the inserted plastic foil (20).
36. An apparatus according to claim 34 or 35, characterized in that the ribbed plungers (90) are resiliently supported.
37. An apparatus according to any one of the claims 29 to 36, characterized in that the side walls (114) and the adjacent edge areas of the negative mould (54) are equipped with a heating means (112).
38. An apparatus according to any one of the claims 27 to 38, characterized in that the working station (50) at the same time constitutes the forming station of the plastic foil (20).
39. An apparatus according to any one of the claims 27 to 38, characterized in that the forming station (30) includes a deep-drawing die (34) into which the plastic foil (20) can be drawn while being pressure-assisted after having been appropriately preheated.
40. An apparatus according to any one of the claims 27 to 39, characterized in that each station of the apparatus is designed so that in one operating cycle a group of receptacles can be further processed, coated and finished.
41. An apparatus according to any one of the claims 27 to 40, characterized in that the receptacles are conveyed through the apparatus connected via the plastic foil (20), and in that a separating means (150) for separating the individual receptacles (156) is connected to the sealing station (130).
42. An apparatus according to any one of the claims 27 to 41, characterized in that the sealing station (130) includes a heated sealing plate (142) the relief and/or the heating means (148) of which is adapted to the shape of the inserted bowl inserts or cardboard blanks (52; 252; 352), resp., such that the sealing between the plastic foil (20) and a cover foil (132) is effected in a circumferentially tight manner by the weld seam outside of the bowl insert or the cardboard blank, respectively.
43. An apparatus, in particular according to any one of the claims 27 to 42, characterized in that the forming station (430) and/or the working station (450) have exchangeable modules.
44. An apparatus according to claim 43, characterized in that the module (430) of the forming station substantially has the dimensions of the heating means of a hard foil packaging system.
45. An apparatus according to claim 43 or 44, characterized in that the modules have substantially equal dimensions.

Images