EP0133834B1 - Container for milky products, and machine and process for its manufacture - Google Patents

Abstract

1. A container at least partially made of plastic, and in particular a container for milk products, the container including a tubular side wall and a bottom fixed to the side wall, the container being characterized in that the side wall (1) is constituted by a rectangular thermoplastic sheet (2) having its short sides welded together to constitute a closed contour, and by two end closure members substantially perpendicular to the side wall and respectively constituting the bottom (4) and the lid (3), each closure member (3, 4) including a groove (10) for receiving an edge of the side wall (1), and the edge being ultrasonically welded in the corresponding groove (10).

Description

The present invention relates to a container intended in particular, but not exclusively for the packaging of fresh dairy products such as yogurts, consisting at least in part of plastic material and comprising a closed side wall and a bottom secured to the side wall, thus that a machine and a method for forming containers of this type.

We know that plastic pots have gradually replaced those made of waxed cardboard or glass. Compared to this last type of container, the advantages of the plastic pot come from a lower weight, a lower brittleness, and the possibility of printing decorations or inscriptions in a relatively simple way. Unfortunately, plastic containers, generally made of polystyrene or polypropylene, do not have the same advantages in terms of use as glass, particularly with regard to insulation from the surrounding environment. Thus, plastics and, in particular polystyrene, are relatively porous for gases normally present in the atmosphere such as oxygen, carbon dioxide or water vapor. These gases can thus diffuse through the wall of the container and affect the quality of the products, even during the consumption period. This results in a rapid degradation of taste.

A first object of the present invention is a container which allows during the period of consumption an integral conservation of the qualities of the product.

In addition, the conservation of the contained product depends, in part, on the precautions which are taken during filling. Another object of the invention is the production of a pot whose asepsis can be obtained by purely physical means, according to current regulatory trends.

In addition, the containers currently used consist of a hollow body which is closed by a lid or a sealed or crimped lid. Thus the pots can be manufactured by blowing or by injection using the properties of plastic materials. This solution makes it possible to obtain the container body in a single operation, then closing it, after filling, with a second operation. Unfortunately, since the places of manufacture of the containers are usually far from the places of manufacture of the products and filling of the containers, these must be transported by trucks which, despite certain stacking devices, carry a lot of volume. empty.

Another object of the present invention is a container which is formed only immediately before filling, which, in addition to optimizing transport, makes it possible to work under perfect aseptic conditions.

US Pat. No. 4,187,768 (SUZUKI) has proposed manufacturing a paper container covered on one of its faces with a thermoplastic film, from a bottom component and a wall component side, these components being assembled by ultrasonic welding. The peripheral edge of the bottom is folded so that this fold is surrounded by another fold formed in the lower part of the side wall. The top of the container is hemmed. The process described in this patent is long, taking into account the need for folding on the one hand and, on the other hand, that the welding time between the paper and the plastic is necessarily longer than between two plastic surfaces. The welding is carried out by a relative displacement of the container and the sonotrode which also requires a lot of time. In addition, the manufacturing time is proportional to the dimensions of the containers.

Another object of the present invention is the manufacture of containers with any sections practically at a rate independent of the dimensions of the containers.

Finally, for practical reasons, fresh dairy products are usually presented in individual or unit doses. However, for the same reasons, but also for commercial reasons, it is desirable that the unit doses be grouped by 2, 4, 8 or 12, with possibly a possibility of mixing, two adjacent containers not containing the same product. The constitution of unit doses and their grouping translate, at the packaging level, into an additional cost for the product thus packaged. In addition, this grouping requires for reasons of mechanical strength, an overpack usually made of cardboard.

Yet another object of the present invention is the production of a container which can be easily grouped with similar containers without it being necessary to join the groups thus formed by an overpack made of cardboard, which makes it possible to achieve a significant saving. .

According to the present invention, the container, in particular for dairy products, constituted at least in part of plastic material, comprising a closed side wall and a bottom secured to the side wall (US-A-4 187 768), is characterized in that that the side wall is constituted by a rectangular thermoplastic sheet whose short sides are welded to form a closed outline and by two styling obturating elements respectively forming the bottom and the cover, substantially pendular to the side wall, each obturating element having a groove inside which is inserted an edge of the side wall, the edge being welded by ultrasound in the corresponding groove.

Thus, the mechanical assembly of the components is done in a way automatically, the sides of the side wall closed by welding penetrating into the grooves and being held there until the welding by ultrasonic provides sealing. It will be noted that the structure of the assembly to be welded forms a concentrator for ultrasound and that the weld thus obtained is of very good quality.

The aforementioned obturating elements will be designated subsequently, respectively by bottom for the lower element welded before filling the pot and by cap or cover for the upper sounded element after filling the pot. These elements are preferably injected independently of the extrusion operation of the side wall.

Thus, the side wall or sidewall, the cover and the bottom are flat during their transport to the place of filling, which allows an optimization of the means of transport used.

• - des moyens de désempilage des feuilles rectangulaires, des éleménts obturateurs formant les fonds et des éléments obturateurs formant couvercles ;
• - des moyens de stérilisation des composants ;
• - des moyens de pliage des feuilles et de soudure par ultrasons sur leurs petits côtés, pour former une paroi latérale ;
• - des moyens d'assemblage d'un bord de la paroi latérale à l'intérieur de la gorge d'un fond sensiblement perpendiculairement au fond ;
• - une tête de soudure pour souder par ultrasons le bord de la paroi latérale dans la gorge du fond, laquelle tête étant une des électrodes de soudure;
• - un doseur pour remplir le récipient ;
• - des moyens pour enclipser un couvercle sur le côté s'insère dans la gorge du couvercle sensiblement perpendiculairement au couvercle ;
• - une tête de soudure pour souder par ultrasons le couvercle sur le côté supérieur de la paroi latérale.

The present invention also relates to a training machine comprising at least one ultrasonic welding electrode (US-A-4 187 768), characterized in that it further comprises:

• - means for destacking the rectangular sheets, shutter elements forming the bottoms and shutter elements forming covers;
• - means for sterilizing the components;
• - means for folding the sheets and ultrasonic welding on their short sides, to form a side wall;
• - Means for assembling an edge of the side wall inside the groove of a bottom substantially perpendicular to the bottom;
• a welding head for ultrasonically welding the edge of the side wall in the bottom groove, which head being one of the welding electrodes;
• - a dispenser to fill the container;
• - Means for clipping a cover on the side is inserted into the groove of the cover substantially perpendicular to the cover;
• - a welding head for ultrasonically welding the cover on the upper side of the side wall.

The present invention also relates to a method of manufacturing a container as specified in claim 8.

All the components of the container can thus be introduced into the machine flat and in the form of sheets. Under these conditions, the asepsis of the components poses no problem and can for example result from exposure to ultraviolet radiation or the like, the rest of the operations being able to continue under an inert atmosphere.

The realization of the sides by extrusion presents many possibilities. It is thus possible to coextrude compounds with two or more layers. These compounds have almost perfect impermeability to external gases, so that good preservation of the product contained in the container is ensured. Printing flat flanks is no problem. In addition, there is no drop of product, which is particularly advantageous in the case of multilayer compounds which are difficult to recycle after a first coextrusion.

It is known, moreover, that during the transport of fresh dairy products, the vibrations due to transport exert on the products a pumping effect which results in an exudation of the serum out of the mass of the yogurt or other product. In order to remedy this drawback, it has already been proposed to conform the yoghurt pots into trunks of cones, the large base of which is at the bottom of the container. This form somehow blocks the yogurt in its upward movements since it must overcome resistance. Unfortunately, she is opposed to stacking empty jars and stacking them. The side wall of the container is perpendicular to the planes of the cap and the bottom. A cone arrangement is not possible in the present case where an effort is made to obtain sufficient mechanical strength to support several thicknesses of full containers.

Preferably the inner wall of the sides has an embossing, formed during extrusion, retaining the yogurt against said wall, avoiding the phenomenon mentioned above during transport.

• - la Fig.1, une vue éclatée d'un groupe de pots selon l'invention ;
• - les Figs. 2 et 3, respectivement une vue de face et une coupe par un plan vertical d'un récipient ;
• - la Fig. 4, une vue d'un flanc à l'état de feuille ;
• - la Fig. 5, une coupe transversale d'un composé multicouches ;
• - la Fig. 6, une vue de l'extrudeuse d'élaboration des flancs ;
• - la Fig. 7, un organigramme de la machine de formation ;
• - la Fig. 8, un schéma montrant l'organisation de la machine ;
• - la Fig. 9, le schéma d'un conformateur de paroi latérale ;
• - la Fig. 10, un schéma du mode d'avancement des pots dans la machine.

Other characteristics and advantages of the invention will appear during the following description of a particular embodiment, given solely by way of nonlimiting example, with reference to the drawings which represent:

• - Fig.1, an exploded view of a group of pots according to the invention;
• - Figs. 2 and 3, respectively a front view and a section through a vertical plane of a container;
• - Fig. 4, a view of a sidewall in sheet form;
• - Fig. 5, a cross section of a multilayer compound;
• - Fig. 6, a view of the sidewall extruder;
• - Fig. 7, a flowchart of the training machine;
• - Fig. 8, a diagram showing the organization of the machine;
• - Fig. 9, the diagram of a side wall shaper;
• - Fig. 10, a diagram of the mode of advancement of the pots in the machine.

Fig. 1 shows, in exploded view, a set of four containers, a container being shown in front view in FIG. 2 and, in vertical section in FIG. 3. A container consists of three parts, namely a sidewall 1 or side wall, a cover or cover 3 and a bottom 4. The cover 3 and the bottom 4 have flanges forming grooves inside which the edges respectively upper and lower of the sidewall 1 are inserted or clipped. Thus, before the welds in the grooves 10 take place, the three elements are automatically and precisely positioned. The bottom 4 and the cover 3 are welded to the lower and upper edges of the sidewall 1 by ultrasonic welding in the grooves 10. This method of welding is preferred to other known means because of its speed and the preservation of the organoleptic characteristics of the container. The side wall 1 is obtained by edge-to-edge welding of a plastic sheet 2 (Fig. 4), fold lines 6a being provided during extrusion.

As is best seen in FIG. 3, the cover 3 has a bottom 12 at a level lower than that of the upper edge of the flank 1. The lower shutter 4 has a bottom 13 which projects from the lower edge of the flank 1. A symmetrical arrangement could be used in which the bottoms would protrude and the lids hollow. The profiles of the cover 3 and the bottom 4 are complementary, that is to say that the surface 13 can be inserted exactly inside a bowl 12, so that in a stack the edges of the sides 1 are exactly in the extension of one another. Thus, the resistance of a stack is maximum and the forces applied during stacking are suitably supported.

In Figs., The pots shown are square section containers. This solution is advantageous insofar as it allows compact groups of containers to be obtained, which saves space. However, any other section is possible and in particular a circular section. As shown in Fig. 4, a sheet 2 intended to constitute a sidewall 1 comprises an internal face 5 and an external face 7. The external face 7 is smooth and it is intended to receive a decoration and / or information on the product contained in the container. The internal face 5 has protruding reliefs 6 forming an embossing. We already know pots with ribbed side walls. However, these ribs are intended only to give a certain rigidity to said wall. The purpose of the striations here is to allow the attachment of the product which is clearly apparent from their diagonal arrangement which is however only an example. The pasty product is thus held against the walls which preserves its homogeneity against the trepidation resulting from the transport of the pots after filling. This embossing also contributes, to a certain extent, to the stiffening of the wall, but the resistance to crushing comes mainly from the perpendicularity of the sidewall and the shutters as well as from their styling assembly and from their joining by welding.

When the sheet 2 is formed by extrusion, the angles of the sidewall are preferably preformed when the latter has a polygonal section. To this end, the zones 6a have a slight radius of curvature.

As has been said previously, it is necessary, in the case of unit doses, that these doses can be grouped with a view to their marketing. An example of grouping is shown in FIG. 1. In general, this is obtained by association of at least two of the shutter elements 3 and / or 4. In the example shown, grouping is obtained by association of four covers. This association is obtained during the conformation by thermoforming or by injection of the covers. To this end, tear-away strips 8 are provided between them. These bands are formed only over part of the length of the inner sides of the covers, which gives off a central orifice 9. This orifice allows the passage of a member (not shown) such as a barbed rod ensuring the maintenance of several thicknesses of groups of containers or transport of a group of containers by hand.

Of course, the containers, arrived at final destination, must be able to be opened easily. To this end, there is provided in the cover 3 a line of least resistance 14 delimiting a cover 11 which can be detached from the cover. To facilitate this separation, a tab (not shown) is incorporated in the cover.

Given the conformations of the bottom 4 and of the cover 3, as well as the resistance to crushing of the vertical walls, it is possible to superimpose several groups of pots so as to form a homogeneous whole. This arrangement makes it possible in particular to improve the filling of trucks or the use of storage areas in a ratio of 1 to 2.2 once the containers are filled. In addition, the overpack boxes are no longer necessary, which leads to a significant cost saving. Indeed, a determined quantity of containers being grouped, both horizontally and vertically, a simple wrapping is sufficient to counterbalance the lateral unbundling forces. In the example which has been represented, the vertical assembly comes from the penetration of a bottom (male) into a cover (female). The reverse arrangement is also possible without departing from the scope of the invention, the vertical forces always having to be transferred from one side 1 to the side 1 immediately adjacent.

Fig. 5 is a cross section of a sheet 2 or of the cover or the bottom. As indicated above, one of the objects of the invention is to allow better preservation of the product contained in the container. The answer to this problem consists in strengthening the gas impermeability of the walls. To do this, increasing the thickness of the walls quickly finds practical limits in manufacturing. The solution adopted may consist in producing the walls of the container in a multilayer complex, at least one layer having good impermeability with respect to the gas which it is desired to avoid diffusion inside the container and, for example, oxygen. . By its structure, said layer forms a barrier opposing the diffusion of one or more gases through the walls. Among the possible barrier materials, mention may be made of ethylene-vinyl alcohol copolymers or EVAL and polyvinylidenes or PVDC. Fig. 5 is a cross section of a multilayer material comprising an outer layer 7, an inner layer 5 and an intermediate layer 15. In some cases, other materials are added to these main layers in order to allow the connection between the different layers. The layers 5 and 7 can be made of polystyrene or polypropylene, the intermediate layer 15 being formed of EVAL or PVDC.

The barrier thus produced makes it possible to preserve the taste of "old-fashioned" products until consumption without using antioxidant chemical preservatives while using modern materials and an extrusion process and not blowing.

Fig. 6 represents the sidewall extrusion operation 1. Three extruders 16, 17 and 18 for example, convey three pasty products in a die or shaping machine 19, from which three layers of materials 5, 7 and 15 come out. A set of rollers 20 ensures the formation of the embossing 6 in what will be the internal surface of the containers. The three-layer sheet is then cooled at 21 and the printing of the face 7 is carried out by inking and printing rollers 23 and 22. The printed face is then dried by an oven 24 and the sheet 2 is cut by a cutter 25 at a pitch equal to the desired height of the containers, the width of the sheet being calibrated to correspond exactly (to the nearest overlap) to the perimeter of the container. The sheets 2 thus cut are counted, stacked and packed in 26. It will be noted that the manufacture of the sheets 2 intended to constitute the sides 1 does not lead to any fall, which is particularly appreciable in the case of compounds with multiple layers.

The covers 3 and the bottoms 4 can be shaped from the same material as the sides 1, or from another material by injection or thermoforming. If necessary, they can be of different colors which allows, by a combination of colors, a perfect identification of the products, even in the case of mixing, that is to say the introduction of different products inside adjacent containers. As indicated above, the covers 3 are grouped in pairs, four, eight or twelve and welded to the containers while remaining grouped. The bottoms 4 can be manufactured in groups, then be unbundled to be mounted individually. The pots can also be assembled by grouping the bottoms.

To fix ideas only, the dosing machines for filling the containers work at a rate of around 40,000 units per hour. It is therefore desirable that the packaging production machines work at a rate of the same order of magnitude. Figs. 7 and 8 are diagrams respectively by blocks and in exploded view of a machine intended to be installed in the production premises of the products to be contained. As indicated above, the components of the containers are produced in any location and conveyed flat and in sheets, which makes it possible to load trucks or wagons without losing space. As shown in Figs. 7 and 8, a machine comprises three destacking stations 27, 28, 29, respectively for the sheets 2, for the bottoms 4 and for the covers 3. Each of these stations is followed by a sterilization stage 34, for example by ultraviolet, this being practiced while the components are flat. The sheets 2, unstacked at 27 are conveyed in the shaping stage 30 where they are folded in four and welded along a generator. In parallel with this operation, a set of bottoms 4 is conveyed in stage 30 and assembled on the upper part of the closed side walls 1 of a group of pots. A pressure causes the edges of the sidewall 1 to penetrate into the groove 10. The assembly thus formed passes in front of an ultrasonic welding head 31 which terminates the pot itself. After turning over, the pots are brought into the filling stage comprising a metering device 32, means for supplying covers or groups of covers and means 35 for welding the covers 3 to the pots. In 36, the filled pots are automatically placed on a pallet.

Fig. 9 shows in more detail the embodiment of the sides 1 from the sheets 2. The de-stacking device 27 is of known type. After passing in front of UV sources 34, the sides of the flank are folded by the conjunction of guides 39 and 41 and welded by the sonotrode 40 along a generator, the short sides of the rectangular sheet being brought edge to edge, slightly overlay.

Fig. 10 is an exemplary embodiment of the driving of the pots 1 in the filling stage 35. The pots, after turning over, penetrate inside a box 45. They are driven by an endless belt 51 animated by an alternative advance movement by a roller 42 itself driven by the cooperation of a motor shaft 44 and a Maltese cross 43. The purpose of this alternative advance movement is to immobilize the pots when filling, then when welding the cover. The pots 1 are simultaneously pushed by a piston 46, driven by a pinion 49 cooperating with an eccentric 48 on which is mounted a cam 50 connected to the piston 46 by a lever articulated around a fixed axis 47. The assembly is adjusted by so that the stroke of the piston 46 is substantially equal to the pitch of the endless belt 51 driven by the roller 42.

• - conformation des corps;
• - pose des fonds;
• - distribution du produit;
• - pose des couvercles.

Given the structure of the containers, the manufacturing machine is advantageously of the modular type, the main modules being the modules of:

• - body conformation;
• - raises funds;
• - product distribution;
• - fitting covers.

Secondary modules are, for example, automatic battery insertion modules; statistical and automatic extraction and automatic station control (as shown schematically at 52 in Fig. 8); automatic loading of a receiving pallet. The movements of the various operations for constituting the packaging do not require a line with continuous kinematics. Moreover, these movements are of small amplitude and of low couples. The precision which can be obtained on the components makes it possible to overcome the complex positioning systems of known machines. In fact, in the machine which has just been described, each pot can constitute its own mark. This result considerably simplifies setting up and maintaining a sterile atmosphere throughout the production chain, which leads to significant savings in equipment. This is all the more so since the elements involved such as the ultrasonic generators (sonotrodes) or the dosers can be standard elements commercially available.

The present invention can be implemented for the packaging of all powdered, liquid or pasty products, food or not. It makes it possible to obtain a combination of characteristics which is not found in known packaging, namely: good preservation of the products, elimination of cardboard overpacks, excellent presentation resulting from the flat decoration of the sides, the possibility of grouping of several containers in a simple operation and their easy unbundling, the maintenance of the product contained in the container by hooking.

In the case where the container contains a dose of product greater than a consumption dose, and for example in the case of chocolate powder or the like, the cover 3 may consist of two parts joined together on a rigid frame secured by ultrasound with the side wall as shown above. These two parts consist on the one hand of a tear-off lid ensuring the inviolability of the container which can be constituted for example by a foil and a cap itself, for example made of polypropylene, mounted on a hinge on the rigid frame. The container can thus be closed after opening and tearing off the cover in order to ensure the preservation of the product.

Claims (8)

1. A container at least partially made of plastic, and in particular a container for milk products, the container including a tubular side wall and a bottom fixed to the side wall, the container being characterized in that the side wall (1) is constituted by a rectangular thermoplastic sheet (2) having its short sides welded together to constitute a closed contour, and by two end closure members substantially perpendicular to the side wall and respectively constituting the bottom (4) and the lid (3), each closure member (3, 4) including a groove (10) for receiving an edge of the side wall (1), and the edge being ultrasonically welded in the corresponding groove (10).

2. A container according to claim 1, characterized in that the internal face of the side wall (1) is embossed (6) while the external face (7) of the side wall (1) is smooth.

3. A container according to claim 1 or 2, characterized in that the external surface (12) of the lid-forming closure member (3) is coplementary to the external surface (13) of the bottom-forming closure member (4), with the external surface (12, 13) of one of the closure members (3,4) being concave and the external surface of the other closure member (4, 3) projecting from the edges of the side surface (1), with the extent of the projection being substantially equal to the convave depth such that after the containers have been filled, closed, and stacked, the edge of one side wall (1) is aligned with the side wall of the adjacent container in the stack.

4. A container according to any preceding claim, characterized in that the lid (3) includes a tear-off cap (11).

5. A container according to any preceding claim, characterized in that at least one of the components (1,3,4) is constituted by multi-layer complex (5, 15, 17) constituting a barrier to gas defusion.

6. A group of containers according to any preceding claim, characterized in that at least one of the closure members (3, 4) is connected to the corresponding closure member (3, 4) of an adjacent container by means of a tear-off strip (8).

7. A machine for forming containers according to any preceding claim, and including at least one ultrasonic welding electrode, the machine being characterized in that it further includes:

means (27, 28, 29) for unstacking the rectangular sheets (2), the bottom-forming closure members (4), and the top-forming closure members (3);

means (34) for sterilizing the components (1, 3, 4);

means (30) for folding the sheet (2) and for ultrasonically welding the short sides thereof to constitute side walls (1);

means for assembling one edge of the side wall (1) inside the groove (10) of a bottom (4) extending substantially perpendicularly thereto;

a welding head (31) for ultrasonically welding the edge of the side wall (1) in the groove (10) of the bottom (4), said head being one of the welding electrodes;

means (32) for filling the container with a protion of product;

means (33) for snap-fastening a lid (3) to the top edge of the side wall (1) so that the top edge enters the groove (10) in the lid substantially perpendicularly thereto; and

a welding head (35) for ultransonically welding the lid (3) onto the top edge of the side wall (1).

8. A method of manufacturing a container, in particular for milk products, the method consisting in:

forming rectangular thermoplastic sheets (2) by extrusion with one of the faces thereof being embossed (6);

making closure members by injection to respectively constitute the lids and the bottoms (3, 4), with each member having a groove (10);

ultrasonically welding together the short sides of the rectangular sheet to constitute a side wall (1) having a closed contour;

inserting the bottom edge of the wall (1) into the groove (10) of a bottom-forming closure member (4) extending substantially perpendicularly to the wall (1), and ultrasonically welding the edge inside the groove (10); and

after filling the container, mounting the lid-forming closure member (3) on the top edge of the side wall (1) in such a manner that the edge is inserted inside the groove of the lid substantially perpendicularly to the lid, and performing ultrasonic welding.

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