GB1593986A

GB1593986A - Method and installation for packing in a sterile medium

Info

Publication number: GB1593986A
Application number: GB5047477A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-12-15
Filing date: 1977-12-05
Publication date: 1981-07-22
Also published as: JPS5391889A; SE433837B; NL7713877A; ES465071A1; IT1116349B; ES473871A1; NL186902B; SE7714142L; JPS581014B2; CH619408A5; NL186902C

Description

(54) METHOD AND INSTALLATION FOR PACKING IN A STERILE MEDIUM (71) We, JEAN ROGER NASICA, a French citizen of 19 avenue Emile Deschanels, 75007 Paris, France and ROLAND TORTEROTOT, a French citizen of "Le petit Chaillot", 78730 Rochefort en Yvelines, France, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- The resent invention relates to a method for pacing in a sterile medium, a method of the type in which containers are formed in a strip of thermoplastic material, a so-called strip for containers, by shaping the thermoplastic material in a heated state in a shaping station.These containers are filled in a filling station, inside a sterile enclosure in which slight excess pressure prevails and which comprises side walls and an upper wall and lower wall at least partly constituted by this strip, then the full containers are covered, without it being possible for their contents to be contaminated by a non-sterile atmosphere, with a sheet, a so-called sheet for lids, whereof at least the side facing the inside of the containers is sterile.

A principal difficulty in known methods of the above-mentioned type is to supply a strip for containers which is both sterile and at the shaping temperature to the inlet of the shaping station. In fact, it is frequently stated that sterilization of the thermoplastic strip is produced by the heat supplied to this strip to bring the latter to the shaping temperature. For satisfactory sterilization, it is necessary to heat the strip to a certain temperature for a certain period of time, the minimum sterilization time being shorter, the higher the sterilization temperature.

Now the conditions for good sterilization can be met by heating the strip simply to the shaping temperature only if the time during which the strip is kept at this temperature is relatively long. For a machine of the known type for packing dairy products in pots shaped by heating, if one wishes to maintain an adequate production rate in the area of economical feasibility, then it is necessary for the thermoplastic strip to travel over a distance of several metres in a heating tunnel. This would result in excessive bulk, an obvious danger of overheating of the strip even in the case of a momentary stoppage of the strip and a long starting-up period with the certainty of an appreciable wastage of material.

Thus, in order to maintain reasonable dimensions and production rates, it may be attempted to sterilize the strip before heating the latter to the shaping temperature. This may be achieved by heating the strip to a sterilization temperature which is appreciably greater than the shaping temperature, for a relatively short period of time, then of cooling the strip before it enters the shaping station. There is thus a danger of excessive softening of the material, hence difficulties in conveying the latter and the appearance of splits or even surface irregularities which may lead to tearing or holes in the strip at the time of shaping. It would also be possible to pass the strip through a bath of sterilizing liquid. However, this makes the installation more complicated and is not readily acceptable when it is a question of packing food products.

The present invention intends to provide a method for packing in a sterile medium, which has none of the aforesaid drawbacks, i.e. a method by virture of which it is possible to supply to the inlet of the shaping station, a strip for containers which is sterile and at the shaping temperature, without the time or the heating device exceeding those necessary simply for heating the material to the shaping temperature, without any danger of excessive softening of the strip and without using a sterilizing product.

This object is achieved by a method in which, according to the invention, one uses a first composite strip constituted by the strip, for containers covered, on its side subsequently intended to form the inner side of the containers, by at least one covering strip, this composite strip is moved towards the inlet of the sterile enclosure, the strip for containers and the covering strip being pressed one against the other in an air-tight manner at least along their edges and with their opposing faces sterile, the covering strip is separated from the strip for containers at the inlet of the sterile enclosure and on leaving the sterile enclosure, the sheet for lids is connected in an airtight manner at least to the edges of the strip for containers comprising the full containers.

The strip for containers is heated to the shaping temperature after separation of the covering strip, on its path between the inlet of the sterile enclosure and the shaping station, a path in which the strip for containers possibly already constitutes a part of the lower wall of the enclosure. This heating is produced for example by passing the strip over a hot surface, in particular one or more heated rollers.

The sheet for lids is constituted by a moving strip for lids which may be sterilized immediately before being supplied to the full containers, which is possible by the action of heat, in particular when this strip for lids is made of metal, for example aluminium.

Whether or not it is made of metal, the strip for lids could advantageously be withdrawn from a composite strip, like the strip for containers. According to another feature of the method according to the invention, one uses a first composite strip constituted by the strip for containers and at least the strip for lids, the latter constituting one or the strip for covering this first composite strip, after separation from the strip for containers, the strip for lids is moved towards the outlet of the sterile enclosure along a path which overhangs that of the strip for containers and the shaping and filling stations and, at the outlet of the sterile enclosure, the containers formed and filled are covered by the lower sterile side of the strip for lids by applying this strip and that comprising the containers one against the other in a sealed manner at least along their edges.

When the strip for lids is withdrawn from a composite strip, whether or not separate from that from which the strip for containers is withdrawn, it may be advantageous to use the strip for lids to form at least one part of the upper wall of the sterile enclosure until the full containers are covered.

The invention also intends to provide an installation for carrying out the method described above, an installation of the type comprising a sterile enclosure having side walls, an upper and lower wall, means for supplying the enclosure with sterile gas at a pressure slightly higher than the pressure prevailing outside the enclosure, first means for conveying a strip of thermoplastic material, a so-called strip for containers, this strip forming at least a part of the lower wall of the sterile enclosure, a station for heating the strip for containers, a station for forming containers in this strip located at least partly in the sterile enclosure and comprising at least one mould able to move vertically below the strip for containers and at least one shaping punch able to move vertically inside a shaping chamber located above the strip for containers, a filling station comprising at least one nozzle supported by a nozzle support and opening out above the plane of the strip for containers, a covering station for covering the full containers with a strip for lids and a sealing station for sealing the covering strip in an air-tight manner on each container around its filling aperture.

This object is achieved by an installation which comprises means for separating from the strip for containers, by a pulling action, at the entrance of the sterile enclosure, a covering strip applied to the strip for containers in an air-tight manner at least along its edges and in which the shaping chamber and the nozzle support are mounted in an air-tight manner on part of the wall of the enclosure which overhangs the plane of the strip for containers, the members of the shaping station located above the shaping chamber, the members of the filling station located above the nozzle support and all the members of the covering and sealing stations being outside the sterile enclosure.

Advantageously, the heating means are located along at least one part of the path of the strip for containers between the entrance of the sterile enclosure and the shaping station.

According to a particular embodiment of the installation according to the invention, the latter comprises guiding means for guiding the strip for lids along a path separate from that of the strip for containers between a first location located upstream of the shaping station and a second location forming the downstream end of the sterile enclosure and passing above the shaping and filling stations.

Further features and advantages of the method and installation according to the invention will become apparent on reading the description given hereafter, by way of example, but in a non-limiting manner, with reference to the accompanying drawings in which: Figure 1 is a very diagrammatic view in elevation and longitudinal section of an installation according to a first embodiment of the invention; Figure 2 is a diagrammatic view in section on line Il-Il of figure l; Figures 3 and 4 are very diagrammatic partial views in elevation and longitudinal section illustrating a second and third embodiment of the invention Figure 5 is a very diagrammatic view in section on line V-V of figure 4;; Figures 6, 7 and 8 are very diagrammatic partial views in elevation and longitudinal section illustrating a fourth, fifth and sixth embodiment of the invention and Figure 9 is a sectional view to an enlarged scale or line IX-IX of figure 7.

Figures 1 and 2 show an installation which comprises a shaping station 12, a filling station 16 and a closing station 18 for respectively forming containers 11 in a strip of thermoplastic material 10, a so-called strip for containers, filling the containers formed in the strip and sealing the full containers still contained in the strip 10, by means of a covering sheet or sheet for lids 20.

The strip 10 is moved stepwise, in a horizontal plane P at least from the entrance of the shaping station. The strip is conveyed by the fact that its edges are gripped by means of grippers 21 (figure 2) supported by endless parallel chain links passing over driving and return wheels (not shown).

Conveying means of this type are known per se (see in particular U.S. Patent No.

3.653.175).

The shaping station 12 comprises at least one and generally, several shaping punches 13 able to move vertically inside a shaping chamber 14 which is located above the plane in which the strip 10 is conveyed in the station 12, the lower edge of the shaping chamber 14 being flush with the surface of the strip 10. Below the strip 10, a mould 15 comprising several compartments 13a, the number of which corresponds to the number of punches 13 and the shape of which corresponds to that of the containers I 1, is able to move vertically between an upper moulding position (figures 1 and 2) in which the upper edge of the mould 15 presses the strip 10 against the lower edge of the shaping chamber and a lower position in which the mould 15 clears a passage for the removal of the containers formed from the shaping station.

The filling station 16, supplied with the product to be packed through a pipe 16a, comprises a nozzle support 17 which has one or more nozzles 17a, the number of which is equal to that of the containers to he filled simultaneously.

The full containers are closed at the station 18 (shown solely in figure 1) by sealing the sheet for lids 20 around the filling aperture of the containers, which sealing is effected by means of a heating electrode 19 and counter-electrode 19a able to move vertically on either side of the plane in which the strip 10 is conveyed.

According to the invention, the strip for containers 10 is withdrawn from a composite strip 22 unwound from a storage roller for example (not shown). This composite strip 22 is constituted by two superimposed strips, the strip 10 and a covering strip 23, which are pressed one against the other in an air-tight manner at least along their edges and the sides of which in facing relationship are sterile.

These two strips can be separated from each other under the action of slight pulling forces, which separation may possibly be facilitated by heating the composite strip to a temperature, referred to as the separation temperature, slightly higher than ambient temperature, but appreciably less than the shaping temperature to which the strip 10 is heated before it enters the shaping station 12.

The strip 10 consists of thermoplastic material and the covering strip 23 may be made from cellulosic material, such as paper or card or of metal, such as aluminium or a metal alloy, or even of plastics material.

The composite strip 22 may be produced in a sterile medium by heating the material constituting the strips 10 and 23 to and maintaining them at the sterilization temperature for a period of time sufficient for their sterilization, then by connecting them, still in a sterile medium, by heatsealing or sealing and in an air-tight manner at least in their marginal areas.

The composite strip 22 may also be produced by extruding the thermoplastic material of the strip for containers on the covering strip 23 heated to the sterilization temperature, or by co-extruding the individual strips forming the composite strip, sterilization of the opposing faces of these individual strips resulting from their manufacture without requiring subsequent treatment.

As shown in figure 1, the covering strip 23 is separated from the strip for containers 10 and passes over a guide roller 24 where it is directed towards a re-winding cylinder (not shown) for possible re-use, this separation being effected at a location which constitutes the inlet of a sterile enclosure 25 (the inner space of which is represented by broken lines in figures 1 and 2).

After entering the enclosure 2.r, the strip 10 passes in succession over a heated drum 26 and a heated return roller 27 which guides the strip towards the plane P along which this strip is conveyed through the remainder of the installation. The drum 26, like the roller 27, is provided with incorporated heating means, for example inner passages 26a (figure 1) for a hot fluid in order to heat the strip 10 to the shaping temperature. The outer faces of the drum and roller are permanently hot and consequently sterile.

Between the entrance to the enclosure 25 and the line where it comes into contact with the roller 27, then from the line where it leaves the roller 27, the strip 10 constitutes the lower wall of the sterile enclosure 25.

Upstream of the shaping station, the enclosure is defined in its upper part by a rigid wall 28 which extends, above the strip 10, from the entrance to the enclosure as far as the shaping chamber 14. Laterally, the enclosure is closed-off by rigid vertical side walls 29 which are connected to the wall 28 and the lower edge of which has a profile whose shape corresponds exactly to that of the path of the strip 10. As it travels, upstream of the shaping station, this strip 10 is gripped by its edges outside the side walls 29 and conveyed by the grippers 21, the paths of the endless chains whose links support these grippers being provided such that the strip 10 slides on the lower edges of the side walls 29 (see figure 2).

Downstream of the entrance to the shaping station, the enclosure is defined in its upper part by a rigid horizontal wall 30 which supports the shaping chamber 14 and the nozzle support 17 and overhangs the plane in which the strip 10 is conveyed.

Vertical walls 31 close-off the enclosure laterally from the upper wall 30 as far as the level of the strip 10, the latter also being gripped, as it travels horizontally, by the grippers 21 outside the side walls.

The enclosure 25 is supplied with sterile air through a pipe 32 connected to orifices (not shown) which open out inside the enclosure, such that a sterile atmosphere prevails in the latter at a pressure slightly higher than the external pressure. The purpose of this slight excess pressure is solely to prevent the external air from penetrating the enclosure by passing between the strip 10 and the rigid side walls 29. 31 and it may be regulated by providing an outlet (not shown) controlled by a valve.

Gaskets 33 housed in a sleeve 34 which, in the shaping station, surrounds the movable rod 14a which supports the punches 13 ensures the seal between the top of the shaping chamber 14 and the outside.

Rigid walls 35, 36 outside the enclosure, extend horizontally below the path of the strip 10 respectively upstream and downstream of the shaping station, the wall 36 being able to move vertically.

As is apparent from figure 1, the parts of the shaping station 12 which are located above the chamber 14, the parts of the filling station which are located above the nozzle support 17 and all the parts of the closing station 18 are outside the sterile enclosure 25.

The strip for lids 20, withdrawn from a storage roller (not shown) and guided by a roller 37, passes through a vertical sterilization tunnel 38 in which at least the side 20a of this strip intended to be directed towards the inside of the containers is subjected to sterilization treatment by the heat liberated by a source 39.

The strip 20 penetrates the sterile enclosure 25, of which it constitutes a part of the end wall with its sterile side 20a facing the inside of the enclosure. Pairs of pressing rollers 40 press the edges of the strips 10 and 20 one against the other and in an air-tight manner downstream of the filling station, the line of contact between these strips constituting the downstream end of the sterile enclosure.

A covering strip 41 withdrawn from a storage roller (not shown) and guided by rollers 42 is possibly pressed on the strip for lids, behind the pressing rollers 40, this covering sheet being welded to the edges of the filling apertures in the containers, above the strip for lids, at the station 18.

The operation of the installation shown in figure 1 will be understood from the preceding description. The strips 22, 10 and 20 are moved stepwise in synchronism. This movement may be produced by various conveying means or by the same pair of chains comprising grippers 21. It is sufficient to provide devices for temporarily opening the grippers at the time of separation of the covering strip 23 and at the time of the application of the strip for lids 20 and the covering strip 41. In this respect, as a variation, it will be noted that pressing of the edges of the strips 10 and 20 one against the other in an air-tight manner could be achieved by the grippers 21 themselves. A solution of this type may in fact be perfectly satisfactory owing to the absence of a risk of contamination of the inside of the containers along the path which may be very short between the outlet of the enclosure and the station 18.

At the time of starting-up, the inner sides of the rigid walls of the enclosure 25, the upper side of the wall 36 mounted in an upper position at the level of the lower edges of the walls 31 and the inside of the tunnel 38 are sterilized, the section of the front end of the strip 10 is pulled as far as the outlet of the enclosure 25 and is covered by the end of the strip 20 and the sterile atmosphere is established inside the enclosure. The stepwise advance of the strip for containers in synchronism with the strip for lids is then started only at the same time as the operation of the shaping and filling stations, after the downwards movement of the movable wall 36 to clear a passage for the shaped containers.

Figures 3 to 9 illustrate other embodiments of an installation for carrying out th invention. Parts common to the devices shown in the figures have the same references and their constructions and operations are described only once.

The installation shown in Figure 3 is identical to that shown in figures 1 and 2 with e,e exception of the supply of the strip for lids 20. In fact, this strip 20 is not sterilized just before its application to the containers, but is withdrawn, like the strip for containers, from a composite strip 50.

The latter is constituted by the strip 20, which may be a thermoplastic strip of the same type as the strip 10 and by a covering strip 51 pressed one against the other in an air-tight manner at least along their edges and with their faces in contact sterile. The composite strip 50 may be manufactured like the composite strip 22. Separation of the strip 51 takes place at the point where the composite strip 50 enters the enclosure 25, only the strip 51 being returned to the outside of the enclosure, whilst being guided by a roller 52 and the strip 20 being pressed against the strip for containers by the pressing rollers 40. In figure 3 it should be noted that at its downstream end, the enclosure 25 is closed off by the sterile sides of the strips 20 and 51 which have just been separated from each other.Drive means (not shown) are provided for moving the composite strip 50 in synchronism with the strip for containers and for supplying the covering strip 51, after its separation from the strip for lids 20, to a re-winding roller.

In the installation shown in figures 4 and 5, the strips 10 and 20 for containers and lids are withdrawn from two separate composite strips 22 and 50, their separations from the respective covering strips 23 and 51 being undertaken in the region of the upstream end of the sterile enclosure 25. Adjacent guide rollers 53, 24 rotating in opposite directions, return the covering strips 23, 51 to the outside of the vessel 25. The sterile sides of these strips 23, 51 may be pressed one against the other, in an air-tight manner at least along their edges before being contaminated by the non-sterile atmosphere. This pressing operation is carried out at the latest at the outlet of the sterile enclosure 25, for example by means of rollers 53, 24. One thus recovers a composite strip formed by the strips 23, 51, which composite strip may advantageously be re-used as it stands.In particular, if one uses two composite strips 22 and 50 of an identical type each constituted by a first and second strip and if the first strip of one and the second strip of the other are used as strips for containers and lids respectively, one thus advantageously recovers a composite strip which is identical to those used and the re-use of which facilitates a considerable saving in material.

After its separation from the covering strip 51 until it is pressed against the strip for containers 10 leaving the enclosure, the strip for lids 20 constitutes the upper wall of the sterile enclosure 25 (shown by shading in figures 4 and 5) and passes above the drum 26, the roller 27, the shaping station 12 and the filling station 16.

The parts of the shaping and filling stations which are above the shaping chamber and the nozzle support supported by the horizontal wall 30 are located inside a transverse tunnel 54 which is connected to the outside and passes through the sterile enclosure 25 whilst being insulated in an airtight manner by a transverse partition closed on itself. This partition is constituted by the wall 30, which forms the lower wall of the tunnel 54 and a wall 55 substantially in the shape of an inverted U which passes above the shaping and filling stations and is connected to the upstream and downstream ends of the wall 30.

Laterally, the sterile enclosure 25 is closed by vertical walls 56 whose upper edge follows the path of the strip 20, whereof the lower edge follows the path of the strip 10 and which comprise openings 56a and 56b which constitute access points to the tunnel 54 (figure 5).

The horizontal walls 35, 36 extend below the strip 10 respectively upstream and downstream of the shaping station 12, the wall 36 being able to move vertically. A wall or roof 57, having a section in the form of an inverted U, extends above the path of the strip for lids 20. The vertical rims 57a, 57b of this wall 57 are in alignment with the side walls 56 and are flush with the upper side of the strip 20. The edges of the strip 20 are thus guided in some way in slots 58 (figure 5), the movement of the strip 20 being able to be produced by means of grippers 21', similar to the grippers 21, which grip the edges of the strip 20 outside the side walls of the sterile enclosure. The edges of the slots 58 may possibly be provided with sealing lips.

As a variation (this is also valid for the embodiments described previously and hereafter) guidance of the strips 10 and 20 along their respective paths in the enclosure, after heating of the strip 10, could be achieved by providing the rigid side walls of the sterile enclosure, on the inner side, with guide slides for the edges of these strips. Transportation may thus be achieved, at least for the strip for lids in the example shown in figures 4 and 5, by means of a conveyor belt comprising lugs engaged in the edges of this strip.

The strips 10 and 20 are connected at the downstream end of the sterile enclosure 25, sealing of the containers then taking place, after superimposition of a possible covering strip 41, as described above.

At the time of starting up, the sides of the walls 57, 55, 30, 35 and 36 which are facing the inside of the enclosure are sterilized, the wall 36 being moved into the upper position, the end sections of the strips 10 and 20 are pulled as far as the outlet of the enclosure and the sterile atmosphere is established in the enclosure. Only then are the strips 10 and 20 moved stepwise in synchronism, the wall 36 is lowered into the lower position and operation of the shaping and filling stations is initiated.

The installation shown in figure 6 differs from that shown in figure 4 by the fact that the strip for lids 20 is the covering strip which constitutes the composite strip 22 with the strip for containers 10, the opposing faces of the strips 10 and 20 being sterile. The latter is a particularly advantageous embodiment, since only one composite strip 22 is necessary.

After their separation, the strips 10 and 20 pass through the transverse tunnel 54 and constitute the lower and upper walls of the sterile enclosure 25. As above-mentioned, the strip 20 is conveyed in synchronism with the strip 10, for example by being gripped by its edges outside the lateral walls of the enclosure, by means of grippers supported by endless chains.

The wall 57, which overhang the path of the strip for lids 20, is extended rearwards, by a vertical rim 57c which extends as far as the point where the strip 22 is separated to form a strip for containers and a strip for lids. This separation is achieved when the strip 22 comes into contact with the heated drum 26, by passing between the latter and a roller 59.

For starting up the installation, one proceeds in the same manner as described previously with reference to figure 6, the formation of the sterile enclosure in this case being effected by separating the end portion of the composite strip 22 into an end portion of the strip for containers 10 and a portion of the strip for lids 20, then by connecting the free ends of these sections at the outlet of the enclosure, in order to close the latter, before proceeding with shaping and filling of the containers by moving the strips for containers and lids in synchronism, whilst separating them from each other at the entrance to the enclosure, as they are moved forwards, under the effect of pulling forces exerted in diverging directions by means for conveying these strips.

In the installation shown in figure 8, the strip for lids 20 is constituted, as in the preceding case, by the covering strip which constitutes the composite strip 22 with the strip for containers 10. However, as in the case of the embodiments illustrated in figures 1 and 3, the upper wall of the sterile enclosure is constituted by rigid wall members.

From the time of its separation from the strip 10, the strip for lids 20 is guided in a passage 60, in the region of the roller 61, until it is re-connected to this same strip 10, at the outlet of the enclosure. The passage 60 passes above the heated drum 26, the heated return roller 27 and the shaping and filling stations 12 and 16.

The bottom wall of the passage 60 partly constitutes the part of the upper wall of the sterile enclosure upstream of the shaping station and is connected by a section of vertical walls 62 to the horizontal wall 30 which supports the shaping chamber 14 and the nozzle support 17.

In the example illustrated (see figure 9), the passage 60 is in the form of a slide. The slide is supplied with sterile gas at a pressure slightly greater than external pressure, from orifices (not shown) which open into its base and are connected to a source of sterile gas.

The base of the slide is located opposite the sterile side of the strip for lids intended to come into sealed contact with the strip for containers. On the upper side, the slide comprises lateral rims 60a, 60b bent inwards to surround the marginal areas of the strip 20. A protection plate 61 may cover the slide above the strip 20 thus constituting a passage in the form of a chute or tunnel in which a sterile atmosphere prevails at slight excess pressure. It will be noted that the circulation of sterile gas in the space between the base of the slide and the sterile side of the strip on the one hand, prevents containers are covered, without their contents hand facilitates guidance of the strip for lids 20 in a floating manner in the slide. It is not necessary to provide special means for transportation of the strip for lids 20, the drive being produced by the simultaneous movement of the connected strips for containers and lids.

Starting up of the installation takes place substantially as described with reference to figure 1.

The embodiment of the invention illustrated diagrammatically in figure 8 differs from that illustrated in figure 7 by the fact that the composite strip 22 comprises, apart from the strip for containers 10 and the strip for lids 20, an intermediate strip 66 interposed between the former, connected to the latter in an air-tight manner at least along its edges and having sterile sides in the same manner as the sides of the strip for containers and lids facing the intermediate strip 66.

The manufacture of the triple composite strip 22 is similar to that of the double composite strip. It may be produced by forming a first double strip in a sterile medium then by adding, still in a sterile medium, the sterilized strip for containers or lids, to this double strip. This production may also be achieved by simultaneously or successively extruding the strip for containers and the strip for lids on either side of the intermediate strip sterilized by heat. In particular, it will be noted that a triple composite strip of this type makes it possible to use only one composite strip in the case where the strips for containers and for lids are made of the same material, which, for a double strip, could pose problems of separation.

In fact, the strip for containers 10 is separated from the two other strips 66 and 20 at the entrance to the passage 60, an entrance which thus also contributes the entrance to the sterile enclosure 25.

The strip for lids 20 is then separated from the intermediate strip 66 by passing the latter through a slot 63 provided in the bottom of the passage 60, downstream of the connection of this passage to the wall 62, i.e. at a location where the bottom wall of the passage 60 does not constitute part of the upper wall of the enclosure. The intermediate strip 66 guided on a roller 64 is re-wound on a roller 65 whereas the strip for lids is then guided alone through the remaining portion of the passage 60 as far as the location where it is pressed against the strip for containers.

By way of variation, it is possible to separate the strip for lids 20 from the two other strips 66 and 10 at the entrance to the sterile enclosure, the strip for lids 20 being moved alone in the passage 60 towards the outlet of the enclosure. The intermediate strip 66 is thus separated from the strip for containers 10 before the latter leaves the drum 26 and is moved out of the sterile enclosure for example through a slot provided in the wall 62.

The method and installation according to the invention, of which several embodiments have been described, makes it possible to pack various food stuffs or pharmaceutical products in a sterile medium.

Naturally, numerous variations could be applied to these examples without diverging from the framework of the protection defined by the accompanying claims.

WHAT WE CLAIM IS:- 1. Method for packing in a sterile medium, according to which containers are formed in a strip of thermoplastic material, a so-called strip for containers, by shaping of the thermoplastic material in a heated state in a shaping station, these containers are filled in a filling station, inside a sterile enclosure in which slight excess pressure prevails and which comprises side walls and an upper and lower wall at least partly constituted by this strip, then the full contamination of this space and on the other being able to be contaminated by the nonsterile atmosphere, with a sheet or strip for lids, whereof at least the side facing the inside of the containers is sterile, characterised in that one uses a first composite strip constituted by the strip for containers covered, on its side ultimately intended to form the inner side of the containers, by at least one covering strip this composite strip is moved towards the entrance of the sterile enclosure, the strip for containers and the covering strip being pressed one against the other in an air-tight manner at least along their edges and with their opposing sides being sterile, the covering strip is separated from the strip for containers at the entrance to the sterile enclosure and at the outlet of the sterile enclosure, the sheet for lids is connected in an air-tight manner to at least the edges of the strip for containers containing the full containers.

2. Method according to Claim 1, characterised in that the covering strip is separated from the strip for containers at a separation temperature lower than the shaping temperature to which the strip for containers is subsequently heated as it travels between the entrance to the sterile enclosure and the shaping station.

3. Method according to one of Claims 1 and 2, characterised in that the strip for containers is heated to the shaping temperature by contact with at least one heating surface.

4. Method according to one of Claims 1 to 3, characterised in that the strip for containers is heated over part of its path, upstream of the shaping station, where it already constitutes at least part of the wall of the sterile enclosure.

5. Method according to one of Claims l to 4, characterised in that, in order to provide the containers with a strip for lids having at least one sterile side, one uses a second composite strip constituted by the strip for lids covered, on its side intended to face the inside of the containers, by a second covering strip, the latter and the strip for lids being pressed one against the other in an air-tight manner at least aiong their edges and with their opposing feces

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the strip for lids 20, an intermediate strip 66 interposed between the former, connected to the latter in an air-tight manner at least along its edges and having sterile sides in the same manner as the sides of the strip for containers and lids facing the intermediate strip 66. The manufacture of the triple composite strip 22 is similar to that of the double composite strip. It may be produced by forming a first double strip in a sterile medium then by adding, still in a sterile medium, the sterilized strip for containers or lids, to this double strip. This production may also be achieved by simultaneously or successively extruding the strip for containers and the strip for lids on either side of the intermediate strip sterilized by heat. In particular, it will be noted that a triple composite strip of this type makes it possible to use only one composite strip in the case where the strips for containers and for lids are made of the same material, which, for a double strip, could pose problems of separation. In fact, the strip for containers 10 is separated from the two other strips 66 and 20 at the entrance to the passage 60, an entrance which thus also contributes the entrance to the sterile enclosure 25. The strip for lids 20 is then separated from the intermediate strip 66 by passing the latter through a slot 63 provided in the bottom of the passage 60, downstream of the connection of this passage to the wall 62, i.e. at a location where the bottom wall of the passage 60 does not constitute part of the upper wall of the enclosure. The intermediate strip 66 guided on a roller 64 is re-wound on a roller 65 whereas the strip for lids is then guided alone through the remaining portion of the passage 60 as far as the location where it is pressed against the strip for containers. By way of variation, it is possible to separate the strip for lids 20 from the two other strips 66 and 10 at the entrance to the sterile enclosure, the strip for lids 20 being moved alone in the passage 60 towards the outlet of the enclosure. The intermediate strip 66 is thus separated from the strip for containers 10 before the latter leaves the drum 26 and is moved out of the sterile enclosure for example through a slot provided in the wall 62. The method and installation according to the invention, of which several embodiments have been described, makes it possible to pack various food stuffs or pharmaceutical products in a sterile medium. Naturally, numerous variations could be applied to these examples without diverging from the framework of the protection defined by the accompanying claims. WHAT WE CLAIM IS:-

1. Method for packing in a sterile medium, according to which containers are formed in a strip of thermoplastic material, a so-called strip for containers, by shaping of the thermoplastic material in a heated state in a shaping station, these containers are filled in a filling station, inside a sterile enclosure in which slight excess pressure prevails and which comprises side walls and an upper and lower wall at least partly constituted by this strip, then the full contamination of this space and on the other being able to be contaminated by the nonsterile atmosphere, with a sheet or strip for lids, whereof at least the side facing the inside of the containers is sterile, characterised in that one uses a first composite strip constituted by the strip for containers covered, on its side ultimately intended to form the inner side of the containers, by at least one covering strip this composite strip is moved towards the entrance of the sterile enclosure, the strip for containers and the covering strip being pressed one against the other in an air-tight manner at least along their edges and with their opposing sides being sterile, the covering strip is separated from the strip for containers at the entrance to the sterile enclosure and at the outlet of the sterile enclosure, the sheet for lids is connected in an air-tight manner to at least the edges of the strip for containers containing the full containers.

sterile and the second covering strip is separated from the strip for lids as the latter enters the sterile enclosure.

6. Method according to Claim 5, characterised in that one uses the strip for lids to form at least one part of the upper wall of the sterile enclosure until the full containers are covered.

7. Method according to one of Claims 1 to 4, characterised in that one uses a first composite strip constituted by the strip for containers and at least the strip for lids, the latter constituting one or the covering strip for this first composite strip, the strip for lids is moved after separation of the strip for containers towards the outlet of the sterile enclosure along a path which overhangs that of the strip for containers and the shaping and filling stations and at the outlet of the sterile enclosure, one covers the containers which have been shaped and filled by the lower sterile side of the strip for lids, by pressing this strip and that comprising the containers one against the other in an airtight manner at least along their edges.

8. Method according to Claim 7, characterised in that one uses a first composite strip constituted by the strip for containers, an intermediate strip, whereof one side is pressed against the side of the strip for containers subsequently intended to form the inner side of the containers and the strip for lids pressed against the other side of the intermediate strip, the three strips being superimposed in an air-tight manner at least along their edges and the sides of the intermediate strip as well as the sides of the strip for containers and lids located opposite the intermediate strip being sterile, the intermediate strip is separated from the strips for containers and lids and discharged to the outside, in a nonsterile atmosphere, by passing the latter through a slot in a wall on one side of which a sterile atmosphere prevails.

9. Method according to one of Claims 7 and 8, characterised in that the strip for lids is passed through a passage in the form of a slide or chute located above an upper rigid wall of the enclosure, at least the part of the passage located below the strip for lids being sterile.

10. Method according to Claim 9, characterised in that one uses a sterile guide slide which covers the strip for lids on either side of the marginal areas as well as adjacent the side intended to come into sealed contact with the strip for containers comprising the full containers.

Il. Method according to one of Claims 9 and 10, characterised in that one uses at least one part of the bottom wall of said sterile passage for producing at least one part of the wall covering the sterile enclosure.

12. Method according to one of Claims 9 to 11, characterised in that the strip for lids is guided in a floating manner through said sterile passage by circulating a sterile gas in the space comprised between the bottom of said passage and the strip for lids.

13. Method according to one of Claims 5 to 7, characterised in that one uses the sterile side of the strip for lids to form the upper wall of the sterile enclosure.

14. Method according to Claim 13, characterised in that one passes the strip for containers and the strip for lids through a transverse tunnel, connected to the outside, passing through the sterile enclosure and in which the upper members of the shaping and filling stations are housed.

15. Method according to one of the preceding Claims, characterised in that the edges of the strip for lids and the edges of the thermoplastic strip are connected by means of grippers.

16. Method according to one of Claims 1 to 14, characterised in that the edges of the strip for lids and the edges of the thermoplastic strip are connected by means of pairs of pressing rollers.

17. Method according to one of the preceding Claims, characterised in that the strip for lids is sealed on each container around its filling opening only after having connected said sheet to the edges of the thermoplastic strip.

18. Method according to one of the preceding Claims, characterised in that in the area of the sterile enclosure, at least the strip for containers, comprising the containers is conveyed, by connecting its edges to conveying members outside the side walls of this enclosure.

19. Method according to one of the preceding Claims, in which one uses a movable strip for lids as the sheet for lids, characterised in that the strip for lids and the strip for containers are guided, at least in the area of the enclosure, by means of a guide slide supported by the side walls of the enclosure and by means of conveyor belts connected to the longitudinal edges of these strips and passing in the guide slides.

20. Method according to one of the preceding Claims, characterised in that a covering strip is applied to the strip for lids in or after the outlet area of the sterile enclosure and this covering strip and the strip for lids are sealed on each container.

21. Method according to one of the preceding Claims, characterised in that, at the time of starting up, the enclosure is closed by means of a section of the strip for containers and, if necessary, of a section of the strip for lids, in order to form the sterile enclosure and a sterile atmosphere is established in this enclosure, before moving the strip for containers stepwise and the strip for containers and the strip for lids are moved in synchronism.

22. Method according to one of the preceding Claims, characterised in that at the time of starting up, the end section of the first composite strip is separated into a section of the strip for containers and a section of the strip for lids, the enclosure is closed by means of the section of the strip for containers and, if necessary, of the section of the strip for lids, the free ends of said sections being connected in an air-tight manner on leaving said enclosure in order to constitute the sterile enclosure and only then does one proceed to the shaping of the containers in the strip for containers and the filling of the containers formed by moving said strips in synchronism, stepwise, whilst separating the composite strip at the entrance to the enclosure, into the strip for containers and the strip for lids, as they are moved forwards.

23. Installation for packing in a sterile medium, comprising a sterile enclosure having lateral walls, an upper and lower wall, means for supplying the enclosure with sterile gas at a pressure slightly greater than the pressure prevailing outside the enclosure, first means for conveying a strip of thermoplastic material, a so-called strip for containers, this strip forming at least one part of the lower wall of the sterile enclosure, a station for heating the strip for containers, a station for forming containers in this strip located at least partly in the sterile enclosure and comprising at least one mould able to move vertically under the strip for containers and at least one shaping punch able to move vertically inside a shaping chamber located above the strip for containers, a filling station comprising at least one nozzle supported by a nozzle support and opening out above the plane of the strip for containers, a covering station for covering the full containers with a covering strip and a sealing station for sealing the covering strip on each container, in an air-tight manner, about its filling opening, the installation being characterised in that it comprises means for separating from the strip for containers, by traction. at the entrance to the sterile enclosure, a covering strip applied to the strip for containers in an air-tight manner at least along its edges and in that the shaping chamber and the nozzle support are mounted in a sealed manner on part of the wall of the enclosure which overhangs the plane of the strip for containers, the parts of the shaping station located above the forming chamber, the parts of the filling station located above the nozzle support and all the parts of the covering and sealing stations being outside the sterile enclosure.

24. Installation according to Claim 23, characterised in that the heatiiig means are located along at least one part of the path of the strip for containers between the entrance to the sterile enclosure and the shaping station.

25. Installation according to one of Claims 23 and 24, characterised in that it comprises guide means for guiding the strip for lids along a path separate from that of the strip for containers between a first location located upstream of the shaping station and a second location forming the downstream end of the sterile enclosure and by passing above the shaping and filling stations.

26. Installation according to Claim 25.

characterised in that the guide means comprise a passage in the form of a slide or chute, which overhangs the plane of the strip for containers and in which the strip for lids is guided, means being provided for producing a sterile atmosphere inside said passage.

27. Installation according to one of Claims 23 and 24, characterised in that it comprises means for separating, at the entrance to the sterile enclosure, the strip for containers and the strip for lids previously applied one against the other in an air-tight manner at least along their edges and in that the strip for lids, on its path between said first and second locations, constitutes part of the upper wall of the sterile enclosure, has a width greater than the distance separating the opposing sides of the lateral walls of the enclosure in the region of said path of the strip for lids and the edges of the latter project beyond said lateral walls.

28. Installation according to Claim 27 characterised in that it comprises second conveying means for moving the covering strip between said first and said second locations by gripping the edges of this strip outside the lateral walls of the enclosure.

29. Installation according to one of Claims 23 to 28, characterised in that it comprises a transverse tunnel which is connected to the outside, which is separated in an air-tight manner from the inside of the sterile enclosure and in which the parts of the shaping and filling stations not located in the sterile enclosure are housed.

30. Installation according to Claim 29, characterised in that the lower wall of the tunnel is said part of the wall of the enclosure on which the shaping chamber and nozzle support are mounted.

31. Method according to one of Claims 5 and 6, characterised in that, after separation of the strips for containers and lids, from their respective composite strips, the sterije side of the second covering strip is pressed against that of the first, in an air-tight manner at least along their edges, before these sides can be contaminated by the nonsterile atmosphere and the composite strip formed in this way is recovered.

32. Method according to Claim 31, characterised in that one uses two similar composite strips each constituted by a first and second strip, the first strip of one and the second strip of the other being used as strips for containers and lids and a composite strip identical to that used is recovered.

33. A method for packing in a sterile medium, substantially as hereinbefore described with reference to the accompanying drawings.

34. An installation for carrying out the method claimed in claim 1, substantially as hereinbefore described with reference to the accompanying drawings.