FR2664853A1 - Thermoformed container provided with an outer decorative and/or reinforcing film - Google Patents

Abstract

The invention relates to a thermoformed container (10), provided with an outer film (20) forming a decoration and/or a reinforcement, characterised in that the film includes portions (21, 22) bent over towards the inside along at least part of two opposite end edges, and in that the adjacent wall (11) of the container includes at least one recess (11a) receiving and immobilising, firmly, the said bent-over portions, these recesses being produced, while the container is being thermoformed, on the said prepositioned film. A method of manufacturing such a container comprises the steps consisting in: providing a mould which includes a thermoforming cavity; immobilising, in the cavity, the decorative and/or reinforcing film, the bent-over portions of which project inwards into the cavity; and thermoforming the container in the cavity, in such a way that its material ends up closely following (matching) the said bent-over portions in order to form the recess or recesses.

Description

 The present invention relates generally to plastic containers having on at least part of their periphery a film or strip of decoration and / or reinforcement. It can be, in particular, without limitation, pots, trays, etc. for food products.

 Conventionally, these reinforcing films or strips are fixed by coating them at least partially with a fusible material, by applying them to the container and by carrying out an appropriate heating.

 A classic problem with this kind of technique stems from the difficulty that there may be in providing the calories necessary for melting the adhesive, from the thermoforming mold of the container or through the plastic material of said container, for it the film is properly pasted. This problem is particularly acute with large container wall and film thicknesses.

 Another drawback of this known technique relates to the recycling of coated containers, recycling which we wish to perform increasingly these days. To promote this recycling, the current trend is to produce decor and / or reinforcement strips in the same material as the pots, and in particular in polystyrene. However, during recycling, there are in all cases significant quantities of the fusible material, which obviously limits the purity and the qualities of the recycled material.

 It should be noted in this regard that, even when the fusible material is provided only in the region of overlap on itself of the decor and / or reinforcement strip, the amount of adhesive is still excessive for good recycling. .

 Finally, another drawback of the known technique is that the gluing of the film, preferably carried out at the same time as the printing of the decoration, requires special machines, which in practice prevents these operations from being carried out immediately upstream. of the step of producing the containers and implies an obvious lack of flexibility in manufacturing, because it is necessary to have different types of films suitably sized and decorated beforehand in order to manufacture different types of containers.

 A known solution to the problems of bonding consists in using a film which seals itself on the container by the heat produced for thermoforming; however, such a self-sealing film must generally be made of a material different from that of the container, which is again undesirable from the point of view of recycling. In addition, this other known technique has the drawback that, in the region of overlapping of the film on itself, the latter is poorly sealed on itself, which degrades the appearance of the finished container.

 The present invention aims to overcome these drawbacks of the prior art and to provide a thermoformed container externally coated with a strip or a film of decoration and or reinforcement, and in which no heat-bonding material or other adhesive agent is necessary for securing the container and its strip.

 Thus, the invention relates to a thermoformed container, provided with an outer film forming a decoration and / or reinforcement, characterized in that the film has inward folds along at least part of two opposite end edges. , and in that the adjacent wall of the container has at least one notch receiving and firmly immobilizing said folds, produced during thermoforming of the container on said prepositioned film.

Preferred, but not limiting, aspects of the present invention are set out below:
- The film may consist of a strip completely surrounding the container, in that the folds are provided along the two edges facing said strip and in that there is provided a single notch receiving and immobilizing the two folds.

 - The folds and the notch can extend essentially vertically in the middle region of one side of the container.

 - The folds and the notch can extend essentially vertically in a corner region of the container.

 the film may consist of a strip extending over part of the periphery of the container, the folds can be provided along two essentially vertical edges opposite to said strip and two notches can be provided which receive and immobilize the two folds respectively .

 the film can extend along two opposite lateral walls and from the bottom of the container, the folds can be provided along two essentially horizontal upper edges of the film and there can be two notches receiving and immobilizing the two folds respectively; extending in the upper region of each of said side faces.

 - The strip may further comprise a plurality of intermediate inward folds extending essentially vertically in the middle region of other sides of the container, in which case there is provided in these regions a plurality of additional notches receiving and immobilizing said intermediate folds.

 - The container and the film can be made of a material of the same kind.

 - Said folds can extend over the entire length of the relevant edges of the film and protrude over a distance of between approximately 0.5 and approximately 2 mm.

According to another essential aspect, the invention relates to a method of manufacturing a container as defined above, characterized by the steps consisting in:
- provide a mold with a thermoforming cavity,
immobilizing in the cavity the decor and / or reinforcement film, the folds of which protrude towards the interior of the cavity, and
- Thermoform the container in the cavity, so that its material comes to closely fit said folds to form the notch (s).

 Thanks to the present invention, it becomes possible, in particular when the film is made of a material of the same kind as that of the container, to carry out recycling under good conditions.

 In addition, since no prior gluing of the film is now necessary, it is possible to carry out the printing of the decoration of the film, for example an inkjet printing assisted by computerized graphic design means, immediately upstream from the manufacturing station for coated containers, which gives much greater flexibility to the whole manufacturing process.

 Furthermore, the invention is also well suited to the production of containers comprising an outer film of expanded plastic. With the conventional bonding techniques mentioned above, the implementation of such films was extremely delicate because such films could in practice neither overlap at their edges, nor be positioned so that these edges are perfectly contiguous .

This resulted in both a defect in appearance of the container and a zone of weakness thereof in this region.

 The present invention allows an easy implementation of this kind of film, used in particular for its reinforcing and thermal insulation qualities for containers containing very hot products, in order to avoid any risk of burns during gripping.

 Finally, the present invention makes it possible to eliminate a conventional defect of the glued films of the prior art, according to which the glue softens when the contents of the container are hot, to induce appearance defects (partial peeling, curling, offset) and / or of mechanical resistance.

Other aspects, objects and advantages of the present invention will appear better on reading the following detailed description of several preferred embodiments thereof, given by way of non-limiting example and made with reference to the accompanying drawings, on which:
FIG. 1 is a perspective view of a container according to a first embodiment of the invention,
FIG. 2 is a view in horizontal section through the container of FIG. 1,
FIG. 2a is an enlarged view of a detail of FIG. 2,
FIG. 3 is a view in horizontal section through a container according to a first alternative embodiment,
FIG. 3a is an enlarged view of a detail of FIG. 3,
FIG. 4 is a view in horizontal section through a container according to a second variant embodiment,
FIG. 5 is a view in vertical section through a container according to a third alternative embodiment,
FIG. 6 is a view in horizontal section through a container according to a fourth alternative embodiment, and
FIG. 6a is an enlarged view of a detail of FIG. 6.

 It will be noted at the outset that, from one figure to another, identical or similar elements or parts have been designated by the same reference signs.

 Referring firstly to Figures 1, 2 and 2a, there is shown a container 10 having a body il for example cylindrical, a flange 12 and a bottom not visible and not referenced. A closure membrane, not shown, can be attached to the top of the container by being peeled off on the upper face of the flange. The container is made of a thermoplastic material suitable for its production by thermoforming, in particular of polystyrene.

 The reference 20 designates a film, here in the form of a strip, which is applied to the external face of the body 11 of the container, as illustrated. The strip 20 can be made of cardboard or preferably of a plastic material of suitable flexibility, for example of polystyrene.

 The strip 20 may be provided around the container 10 either for the purpose of mechanical reinforcement thereof, or to decorate it with any appropriate sign or graphic, or again both for the purpose of reinforcement and decoration.

 According to an essential aspect of the invention, the strip 20 is fixed to the outside of the container 10 without using adhesive material or the like. To achieve the fixing, each of the lateral end edges of the strip is folded inwards for a short distance before it is put in place. These inward folds are produced, for example, by hot bending using an appropriate tool. They make with the adjacent part of the strip an angle preferably of the order of 900. The strip 20 is then immobilized in a determined position against the inner wall of an appropriate thermoforming mold, of the type comprising a cavity for placing in the shape of the container, so that the folds, indicated at 21 and 22 in FIG. 3, protrude towards the interior of the cavity.

 The container 10 proper is then produced by thermoforming, in a conventional manner, and the wall of the container being formed comes closely to marry the two folds 21 and 22 juxtaposed.

 At the end of the operation, the thermoplastic material of the container having hardened, the folds 21 and 22 are firmly trapped in the complementary notch lla defined by the body 11, which ensures that the strip is held in place quite satisfactorily 20 on the container.

 It may be noted here that the strip 20 can be immobilized in the cavity without it being necessary to provide auxiliary means for temporarily maintaining the latter. Indeed, by its elasticity, which tends to bring it back into its original rectilinear profile, the strip is applied tightly against the wall of the cavity. In addition, the folds 21 and 22 projecting inwards, which are in this position brought opposite one another, make it possible to prevent the two corresponding edges of the strip from overlapping .

 In the example illustrated in FIGS. 1 and 2, the fixing of the strip 20 by its lateral edges is carried out along a vertical located approximately in the middle of a right lateral wall of the body 11.

 In the variant shown in Figures 3a and 3b, the folds 21, 22 and the associated notch of the body 11 are located at a corner of the body 11, this being obtained by an appropriate positioning of the strip 20 in the cavity of the mold before thermoforming.

 This variant embodiment is advantageous according to two aspects: first, the junction between the two edges of the strip is less visible than when it is located in the middle of a side wall; the appearance of the decorated container is improved because all of its lateral faces are thus perfectly smooth and keep the decoration of the strip all its sharpness. Then, the fact of transferring to an angle the notch 11a, which constitutes a slightly protruding rib inside the container, minimizes the difficulties of extracting the contents of the container with a spoon, in particular in the case where the container is a yoghurt pot.

 In the embodiments of Figures 1 to 3, the strip 20 of decoration and / or reinforcement extends over the entire periphery of the body 11 of the container.

 Of course, provision can be made according to the invention for a decoration strip which extends over only part of this periphery. This case is illustrated in FIG. 4, where it can be seen that the strip 20 has a horizontal length approximately equal to the width of a side wall of the container 10. Here again, the two interior folds 21, 22 are provided. and the fixing of the strip 20 is ensured following the thermoforming of the container, said folds being individually trapped by two respective notches 11a, 11b formed during thermoforming when the pot material has come to "drape" the folds.

 The invention also applies to different strip configurations. There is shown in Figure 5 a container 10 which can be of the kind food container, for example of elongated shape (in a direction perpendicular to the drawing sheet).

 In this case, the film 20 can extend on the two long sides and on the bottom of the container, as illustrated. As a corollary, the folds 21, 22 are provided at the two horizontal edges of the film 20, parallel to the major axis of the tray.

 The production of the container provided with its decor and / or reinforcement film is similar to what has been described above. Two notches 11a, 11b are formed around the folds 21, 22 during thermoforming, these notches holding the film in place by its two edges.

 Furthermore, the Applicant has observed during its tests that the presence of the two folds 21, 22 and the corresponding notch 11a contributed to considerably stiffen the pot in the direction of these parts, that is to say vertically on Figures 1 to 4.

 Another alternative embodiment, shown in FIGS. 6a and 6b, consists in making use of this stiffening effect. To this end, the strip 20 comprises, as previously, preferably contiguous folds 21 and 22. These folds are situated vertically in the middle of a lateral face of the container.

 However, the strip 20 also includes, in positions preferably corresponding to the level of the respective media of the other lateral faces of the container, folds 23 which are illustrated in particular in FIG. 6a. These folds include, as shown in this figure, two branches 23a, 23b extending essentially perpendicular to the general direction of the strip and joined by a return area at 1800 denoted 23c. As for the two end folds 21, 22, the thermoforming of the container on the prepositioned strip placed in the mold causes the creation of a notch 11a at each intermediate fold 23, firmly immobilizing the latter.

 In this way, the four sides of the container are made rigid while using a single strip. This embodiment is particularly advantageous when it is desired to produce containers of fairly large dimensions, for example with a capacity of one liter, of polystyrene with thin walls. Thanks to the stiffening provided as described above, such an embodiment becomes possible by using a strip 20 whose thickness remains moderate.

 Of course, the present invention is in no way limited to the embodiment described above and shown in the drawings, but a person skilled in the art will know how to make any variant or modification in accordance with his spirit.

 In particular, the materials chosen for the strip and the container itself may be entirely arbitrary, identical or different, the essential criteria with regard to the present invention being that the material of the container is thermoformable and that the material of the strip or of the outer film is such that the folds 21, 22 and possibly 23 do not deform excessively during thermoforming.

 It is clear that a container produced in accordance with the present invention, with the same thermoplastic material for the container part proper and the strip, is particularly suitable for recycling because strictly no foreign material contaminates the recycled material.

 Furthermore, the shape and dimensions of the film in the region of its folds can be entirely arbitrary, in particular undergoing any modification with respect to the description given above and to the drawings in order to seek any particular aspect.

 In this regard, it may be noted that the folds 21, 22 may extend over only part of the length of the edges considered of the film, while ensuring satisfactory maintenance.

Claims (10)

 1. Thermoformed container (10), provided with an outer film (20) forming a decoration and / or reinforcement, characterized in that the film has folds (21, 22) inwards along at least part of two opposite end edges, and in that the adjacent wall (11) of the container has at least one notch (11a) receiving and firmly immobilizing said folds, produced during thermoforming of the container on said prepositioned film.  2. Container according to claim 1, characterized in that the film consists of a strip (20) completely surrounding the container, in that the folds (21, 22) are provided along the two edges opposite said strip and in that there is provided a single notch (11a) receiving and immobilizing the two folds.  3. Container according to claim 2, characterized in that the folds (21, 22) and the notch (11a) extend essentially vertically in the middle region of one side of the container.  4. Container according to claim 2, characterized in that the folds (21, 22) and the notch (11a) extend vertically in a corner region of the container.  5. Container according to claim 1, characterized in that the film consists of a strip (20) extending over part of the periphery of the container, in that the folds (21, 22) are provided along two edges essentially vertical opposite said strip and in that there are provided two notches (11a) receiving and immobilizing the two folds respectively.  6. Container according to claim 1, characterized in that the film (20) extends along two opposite side walls and the bottom of the container, in that the folds (21, 22) are provided along two edges substantially horizontal upper film and in that there are provided two notches (11a) respectively receiving and immobilizing the two folds and extending in the upper region of each of said side faces.  7. Container according to claim 3, characterized in that the strip (20) further comprises a plurality of intermediate folds (23) inwardly extending essentially vertically in the middle region of other sides of the container (10) and in that there is provided in these regions a plurality of additional notches (11a) receiving and immobilizing said intermediate folds.  8. Container according to one of claims 1 to 7, characterized in that the container (10) and the film (20) are made of a material of the same kind.  9. Container according to one of claims 1 to 8, characterized in that said folds (21, 22) extend over the entire length of the relevant edges of the film and protrude over a distance between about 0.5 and about 2 mm.  10. Method for manufacturing a container according to one of claims 1 to 9, characterized by the steps consisting in:  - provide a mold with a thermoforming cavity,  immobilizing the decor and / or reinforcement film in the cavity, the folds of which protrude towards the interior of the cavity, and  - Thermoform the container in the cavity, so that its material comes to closely fit said folds to form the notch (s).