Abstract:
A sealed enclosure is provided with a valve at least part of which extends inside the enclosure and is formed between two flexible sheets extending between two opposed edges of the enclosure and being connected along two non-converging connection lines to define therebetween a duct upon spacing apart the flexible sheets from one another to allow the passage of a fluid between the inside and the outside of the enclosure. The sheets are arranged to be applied against one another upon ceasing of the application thereto of a force tending to hold them apart, thus preventing said fluid from leaving the enclosure. The sheets are sealingly connected to one another with each of the non-converging connection lines forming said duct at the opposite edges of the enclosure, the edges of the sheets adjacent to the inlet end of the duct being sealingly connected to the wall of the enclosure. Therefore, the opposed edges of the enclosure between which the flexible sheets extend are assembled to one another such that the corresponding edges of these flexible sheets situated between the edges of the enclosure are, on the one hand, assembled to one another, and on the other hand, to the adjacent edges of the enclosure. Also, the connection of the edge adjacent to the inlet end of the duct, of at least one of said flexible sheets, is constituted by an assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a Divisional of U.S. patent application Ser. No. 08/702,683, filed Sep. 3, 1996, the disclosure of which is being incorporated herein by reference in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a sealed enclosure provided with a valve at least part of which extends inside the enclosure and is formed between two flexible sheets connected along two non-converging lines to form therebetween a duct upon spacing apart said flexible sheets from one another to allow the passage of a fluid between the inside and the outside of the enclosure, said sheets being arranged to be applied against one another upon ceasing of the application thereto of a force tending to hold them apart, thus preventing said fluid from leaving the enclosure. This invention also relates to a method of manufacturing this enclosure as well as a method of packaging a beverage.  
           [0004]    2. Description of the Prior Art  
           [0005]    Sealed enclosures of this type have already been proposed, provided with a valve which is in extension of the enclosure&#39;s wall, thereby avoiding problems relating to securing a fitted-on valve. Such enclosures are described notably in GB 826,784 and FR 1 338 549. The latter document proposes to make the enclosure out of a tubular element. This solution has the drawback of necessitating folding over the tubular element in order to place the valve inside the enclosure. This solution does not lend itself to be manufactured using automated mass-production lines that generally include folding, welding and cutting stations.  
           [0006]    As for GB 826,784, its principal drawback resides in the fact that, in case the enclosure is used for packaging a beverage, the beverage must be introduced via the valve&#39;s orifice which necessarily is of small section because it is designed for the passage of a drinking straw. Because of this, the speed of filling the enclosure is necessarily reduced due to the small section of the passage, which limits the speed of the production line. Such a solution is evidently not economically viable.  
           [0007]    Another drawback is that this enclosure is not adapted to be produced using machinery which is known, available or adaptable to the production thereof.  
           [0008]    The aim of the present invention is to at least partly remedy the above-mentioned drawbacks.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    This invention concerns a sealed enclosure of the above-mentioned type. It also concerns a method of packaging a beverage in this sealed enclosure. Lastly, it concerns a method of manufacturing the sealed enclosure.  
           [0010]    An advantage of the proposed solution is to enable the sealed enclosure to be manufactured with its valve integrated in a single wall of the enclosure, which enables use of existing production lines starting with a flat plastic film. When the enclosure is for packaging beverages, the enclosure can be filled at a high rate via an orifice which is of much greater section than the valve. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The accompanying drawing shows, schematically and by way of example, several different embodiments and variations of the sealed enclosure, as well as the methods of manufacture thereof according to the present invention.  
         [0012]    FIGS.  1  to  4  are perspective views illustrating different production steps of one embodiment of enclosure.  
         [0013]    [0013]FIG. 5 is a cross-section along line XV-XV of FIG. 4.  
         [0014]    FIGS.  6  to  12  are perspective views illustrating different production and filling steps of the first embodiment.  
         [0015]    FIGS.  13  to  17  are perspective views illustrating different production and filling steps of the second embodiment.  
         [0016]    [0016]FIGS. 18 and 19 are perspective view of two variations of FIG. 12.  
         [0017]    FIGS.  20  to  20   f  are partial views of a variation of the embodiments of FIGS. 1 and 2 or  7  and  9 .  
         [0018]    [0018]FIGS. 21 a  to  21   d  are partial view of another varied embodiment.  
         [0019]    [0019]FIG. 22 is a cross-section of yet another variation.  
         [0020]    [0020]FIG. 23 is a perspective view of another variation of the embodiment illustrated in FIG. 18.  
         [0021]    [0021]FIG. 24 is a plan view of a variation of the valve applicable to any one of the embodiments which serves as a packaging enclosure for a liquid.  
         [0022]    [0022]FIG. 25 is a perspective view illustrating a method of manufacturing a varied type of sealed enclosure according to the invention.  
         [0023]    [0023]FIG. 26 is a cross-section of this varied enclosure along line XXVI-XXVI of FIG. 25.  
         [0024]    [0024]FIG. 27 is a perspective view of another variation of the method of manufacturing a varied type of sealed enclosure.  
         [0025]    [0025]FIG. 28 is a cross-sectional view along line XXVIII-XXVIII of FIG. 27.  
         [0026]    [0026]FIG. 29 is a perspective view of a last type of varied method of manufacture of another type of sealed enclosure.  
         [0027]    [0027]FIG. 30 is a cross-sectional view along line XXX-XXX of FIG. 29.  
         [0028]    [0028]FIG. 31 is a perspective view of a variation of FIGS. 4 and 5.  
         [0029]    [0029]FIG. 32 is a cross-sectional view of a last varied type of the sealed enclosure. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    As shown in FIG. 1, to start with a sheet  24  is folded a first time to form a strip  24   a.  Preferably simultaneously, welds  28  and  29 ′ are made as well as two oblique parallel welds  30  and  31  extending from one weld  28  to the other  29 ′ to form the valve. For this purpose, the welds  28  and  29 ′ stop short between the welds  30  and  31 . Then, a cut-out  32  is provided in the first fold between these welds  30  and  31  to form a traversing passageway therebetween. The weld  28  stops a given distance away from the free edge of the strip  24   a.    
         [0031]    The sheet  24  is folded over again adjacent the weld  28  (in the direction of arrow F—FIG. 1) to form a strip  24   b,  and the weld  29 ′ is fixed to the sheet  24  by a new weld  29  (FIG. 2) which now connects together the three thicknesses of the sheet  24 . Like the initial weld  29 ′, this new weld  29  stops between the valve&#39;s oblique welds  30 ,  31 .  
         [0032]    Then, sheet  25  (FIG. 3) is placed onto sheet  24  and these sheets are welded together to form a pocket between these sheets, on the one hand, and welds  33 , on the other hand, to receive an object to be packaged. Preferably, the lateral edges of this pocket, closed by the welds  33 , flare out to facilitate positioning of the object in the pocket. The sheets  24  and  25  thus form the inside wall of the sealed enclosure. Two openings  34  are then formed, for a purpose to be described later.  
         [0033]    Then, two sheets  26 , 27  are placed respectively on the sheet  24  and on the sheet  25  (FIG. 4). A weld  35  is formed between one edge of sheet  26  and the adjacent edge of strip  24   a.  A weld  36  is formed between the two adjacent edges of sheets  25  and  27  and another weld  37  is formed parallel to the previous ones between the adjacent edges of the four sheets  24 , 25 , 26  and  27  (FIG. 5). Then two further parallel welds are formed (one of which,  38 , is visible on FIG. 4), extending along the two other edges of the sheets  24  to  27 , hence finishing the container. Given that the four sheets  24  to  27  are welded together on three sides and two-by-two along the fourth side, and that the valve opens out between the sheets  24  and  26 , if the sheets  24  and  25  were not pierced with openings  34 , only the space between the sheets  25  and  26  could be inflated. These openings  34  thus serve to place the space between the sheets  25  and  27  into communication with the valve arranged between the strips  24   a,   24   b  of sheet  24 .  
         [0034]    In a variation, the enclosure, instead of having a sealed pocket between two double walls, could have a single wall, in other words it would comprise only the sheets  24  and  26 , and sheet  24  would not be pierced by openings  34 . Such an enclosure could serve for packaging a liquid, for example a beverage.  
         [0035]    Due to the design of the container illustrated in FIGS.  1  to  4 , the outer walls  26 , 27  may be made of different materials to those of the sheets  24 , 25 . Consequently, the outer walls could, for example, be thicker. It would also be possible to envisage that the outer walls would be rigid or semi-rigid shells.  
         [0036]    In the given examples, the enclosure&#39;s walls are weldable, notably by ultrasounds, and are based on polythylene (PE) or linear low density polytheylene (LLDPE), preferably constituted of stratified PE/X/PE, where X is constituted of an air-tight barrier such as polyethylene vinyl alcohol (EVOH), polyamide (PA) or oriented polyamide (OPA). Of course, welding could be replaced by gluing although this would be more complicated to implement. A PE/X/PE configuration enables welding onto both sides of the sheet.  
         [0037]    It can also be noted that the weld lines  28  and  29  connecting the weld line  29 ′ to sheet  24  are not indispensable. It has however been observed that these weld lines are useful in as much as they ensure proper positioning of the valve inside the enclosure during inflation. It has also been observed that it is preferable to connect the bottom of the pocket to the bottom of the enclosure. However, this expedient is also not indispensable and the sheets  24  and  25  could be interrupted level with the weld line  33  defining the bottom of the pocket.  
         [0038]    Of course, apart from the sheets&#39; folding lines which are straight in order not to create problems of wrinkling in the folded strips, the remainder of the enclosure&#39;s periphery may have a shape other than quadrangular. For this, it suffices to cut the sheets to the desired shape, before or after welding, whereby the weld lines follow this shape.  
         [0039]    It should further be noted that the container according to FIGS.  1  to  5  could also be provided with a part extending out of the enclosure beyond at least one of the welds  35  or  36 , this part being adapted to form a handle, for example, or to form a flap protecting access to the valve.  
         [0040]    [0040]FIG. 6 shows a quadrangular sheet  40  in which an orifice  41  has been pierced and covered with a cover  42 .  
         [0041]    This sheet  40  is cut from a roll which is unrolled while flat on a horizontal or vertical production line in a hydrogen peroxide bath in order to ensure aseptic treatment of the packaging material. Unwinding of the film or sheet takes place parallel to the welds from the top to the bottom of the sachet. The valve whose production will firstly be described is made in steps in the direction of unwinding of the coil of film.  
         [0042]    [0042]FIG. 7 shows this same sheet  40  of which a marginal strip  40   a  has been folded onto the front face of the sheet  40  level with the center of orifice  41 . The marginal strip  40   a  is welded by two oblique parallel welds  43 , 44  limiting what will become the valve, and by welds  45 , 46 , 47  parallel to the folding line of the marginal strip  40   a  and connecting each end of the welds  43 , 44  or the two lateral edges of sheet  40 .  
         [0043]    [0043]FIG. 8 shows the fold of the marginal strip  40   a  in the opposite direction (arrow F) relative to the part  40   b  of sheet  40  to which it has been welded.  
         [0044]    [0044]FIG. 9 shows the weld  46   a  of sheet  40  to the strips  40   a  and  40   b  along the same weld line as weld  46 . The purpose of this weld  46   a  is to allow a drinking straw to be guided between the oblique weld lines  43 , 44  which define the valve.  
         [0045]    [0045]FIG. 10 shows the formation of a sachet which forms the sealed enclosure. In addition to the sheet  40  and the valve whose production steps have just been described, the sachet comprises a quadrangular sheet  48  of the same dimensions as the sheet  40  provided with its valve and a bellows-like folded part  49  designed to form the bottom of the sachet allowing it to be stood vertically on a horizontal surface.  
         [0046]    To enable the folded part  49  to be welded to the lower ends of sheets  40  and  48  without the outer faces of the folded part becoming welded together, the folded part is made of a stratified material whose internal layer is a thermoplastic material, for example polyethylene whose external face is made of a thermo-hardenable material, for example OPA.  
         [0047]    [0047]FIG. 11 shows two lateral welds  50 , 51  connecting together the sheets  40  and  48 , and two bottom welds  52 , 53  connecting the folded part  49  to the sheets  48  and  40  respectively. However, the upper edge of the sheets  40  and  48  is not welded, leaving an opening  54  through which the enclosure can be filled.  
         [0048]    Finally, FIG. 12 illustrates the finished container with the upper edges of sheets  40 , 48  connected by a weld  55 . A drinking straw  56  is engaged in the duct provided between the valve-forming welds  43  and  44  and is furthermore attached onto the outer face of sheet  40  by an adhesive type  57 .  
         [0049]    To consume the beverage, it suffices to remove the adhesive  57  to disengage the drinking straw  56  and push this into the inside of the enclosure by perforating the cover which may by a thin patch of aluminium. When the drinking straw  56  is removed, the two walls of the channel arranged between the welds  43  and  44  close again and, if the enclosure is turned upside down, the pressure exerted by the liquid hermetically closes the channel. As a variation, in place of the opening  41  and the cover  42  it is possible to replace the opening by a pre-cutting of the film  40 .  
         [0050]    From the preceding description, it can be seen that the production method enables a perfectly aseptic packaging of the beverage.  
         [0051]    The embodiment of FIGS.  13  to  17  relates to the manufacture of sachets with bellows-like folded parts in the sides and which is designed to be produced on a production line having a machine axis parallel to the sachet&#39;s vertical axis. The valve must be so positioned that the folding operations are carried out continuously along the machine&#39;s axis. This constraint implies positioning the valve on a side part of the sachet.  
         [0052]    Apart from this difference, production of the valve shown in FIG. 13 corresponds in all respects to what is described and shown with reference to FIGS.  5  to  9 . For this reason, the same reference numbers have been used for this part of the enclosure.  
         [0053]    To make this enclosure, a sheet  60  is provided having the same dimensions as sheet  40  but having a bellows-like folded part  61 , 62  on each of its opposed lateral edges. Four welds are made (FIG. 15), two welds  61 , 62  to the sheet  40  and two welds  64  to rigidify the sachet.  
         [0054]    [0054]FIG. 16 shows the bottom-end weld  65  whereas at the top of the sachet an opening  66  is left for filling purposes. The sachet closed by a weld  67  (FIG. 17) can be placed on the bottom-end weld  65  which will flatten under the weight of the liquid, whereas the valve-forming channel provided between the welds  43  and  44  allows access to the beverage after perforating cover  42 .  
         [0055]    The variation of FIG. 18 shows the sachet of FIG. 12 wherein the weld  46 a has been dispensed with, and the valve channel provided between welds  44 ′ and  50  (parallel to the edge of the sachet instead of oblique) is longer so as to form between the welds  44 ′, 45 ′ and  51  a pocket designed to receive a drinking straw  56 . As the container formed by the sealed enclosure is designed specially to allow drinking the beverage several (subsequent) times, it is useful to provide a storage space for the drinking straw  56  which is required to penetrate into the enclosure through the channel formed between welds  44 ′ and  50 . The drinking straw containing pocket can be fitted with an adhesive-band type closure system arranged along its upper edge instead of the weld  46   a  of FIG. 12, or a closure device known under the Trademark Mini-grip®.  
         [0056]    According to another variation, a pocket  68  can be provided in one of the sheets  40  or  48  forming a wall of the enclosure, which pocket serves to house a drinking straw.  
         [0057]    The heretofore described sealed enclosure is made from a sheet forming at least one wall of the enclosure, in a marginal strip from which a valve is produced by folding and welding, as described above, which valve enables control of the flow of a fluid into or out of the sealed enclosure and to maintain the enclosure closed.  
         [0058]    This embodiment necessarily presupposes that the sheet forming this wall of the enclosure and the valve are all made in the same material of the same thickness. However, to be able to close properly, the valve must be made of a very flexible material that is as thin as possible. On the other hand, it may be desirable for the enclosure wall to be thicker and preferably made of a stratified material such as PE/X/PE, where X is a gas-tight barrier such as polyethylene vinyl alcohol (EVOH), polyamide (PA) or oriented polyamide (OPA), whereas such a stratified material is not particularly suitable for the valve.  
         [0059]    For this reason, it was envisaged to make the sheet  70  (FIG. 20) and the marginal strip  71  in two different thicknesses of the same material or different materials. Thus, the sheet  70  will be made in one of the above-mentioned stratified materials, whereas the marginal strip will be formed of a single layer of PE. This sheet  70  and this marginal strip are unwound from two spools and are arranged edge-to-edge (FIG. 20 a ) then welded together by a weld  72  (FIG. 20 b ). Then the marginal strip  71  is folded along the middle of its width (FIG. 20 c ). A weld  73  is made along the fold and two parallel welds  74 , 75  between the weld  73  and a weld  76  parallel thereto as in the previous embodiments, this weld  76  being interrupted between welds  74  and  75 .  
         [0060]    Next (FIG. 20 e ), the weld  73  is cut between the parallel welds  74 , 75  to form the channel and two cutouts  74   a  and  75   a  are made in the middle of the width of welds  74 , 75 . These cut-outs are designed to free a part of the length of the valve from the marginal strip  71  in which it is formed, which enables a better efficiency in the pressure exerted on the faces of the valve for the purpose of closing it, as explained previously. It should be noted that these cut-outs may advantageously also be made in the valves of the previous embodiments.  
         [0061]    Lastly, the marginal strip  71  in which the valve is formed is folded over onto the rear face of the sheet  70  (relative to FIG. 20 e ), as shown in FIG. 20 f,  whereafter the enclosure is finished as in the preceding embodiments, by welding another identical sheet to the sheet  70  along the free edge of the marginal strip (FIG. 20 f ) and along the three sides of the sheet  70  non-adjacent to this free edge, hence closing the enclosure on four sides.  
         [0062]    The variation of FIGS. 21 a  to  21   d  differs from the preceding one simply in that the valve, made of a material differing from that of the sheet  70 ′, designed to form a wall of the sealed enclosure, is formed as previously by folding and welding before being secured to the sheet  70 ′. Starting from a separate strip  71 ′ folded in two (FIG. 21 a ), a weld  73  is formed along the fold. Non-converging welds  74 , 75  are made, as well as a weld  76  connecting one of the ends of the non-converging welds to the transverse edge of the strip  71 ′. A cut-out is made between the welds  74 , 75  and the weld  73  of the strip (FIG. 21 c ), these cut-outs  74   a,   75   a  preferably being made part of the way along the welds  74 , 75 . Then (FIG. 21 d ), one of the free edges of the strip  71 ′ is welded to one edge of the sheet  70 ′ and the enclosure is finished by welding a second sheet (not shown) at least in the case of a single-walled enclosure, as in the preceding embodiments. It is also of course possible to secure one or more bellows-like folded parts between the sheets, as previously described.  
         [0063]    As another alternative to the embodiments of FIGS. 20 and 21, the same result can be achieved starting, as before, from a single multilayer sheet  84  having a different marginal part, for example a monolayer  85  in which the valve is formed as described previously.  
         [0064]    The embodiment of FIG. 18 proposes to provide a pocket to house therein a straw  56  for drinking the liquid contents of the enclosure. FIG. 23 illustrates a variation of this embodiment in which the single-walled enclosure with the valve is of the same type as in the embodiment of FIG. 11. However, this variation differs in that an external pocket is provided between an external wall of the enclosure and third wall  77  welded on three sides  78 , 79 , 80  to the corresponding edges of the enclosure, but stopping short a certain distance from the fourth side  81 , thus enabling access to the inside of the pocket adapted to receive a drinking straw  82 . The opening of this pocket is closed by an auto-adhesive tape  83  which extends from the edge  81  of the enclosure down to below the upper non-welded edge of the sheet  77 . In this variation, the sheet forming the wall of the enclosure adjacent to the pocket may be the sheet forming part of the valve, similar to the valves of the previously described embodiments. Due to the fact that this wall is covered by the pocket-forming sheet  77  and by the adhesive tape  83 , the sheet forming this wall and the valve may be made of a thinner material than that forming the other wall of the enclosure and the sheet  77 .  
         [0065]    The variation illustrated in FIG. 24 shows an enclosure  90  provided with a valve formed between two parallel welds  86 , 87  extending between two opposite edges of the enclosure  90 . The parallel welds  86 , 87  are arranged in such a manner as to each form a progressive thickness  86   a,   87   a  in the valve&#39;s channel  91 , reducing the section thereof in funnel-like manner to a point where the welds  86 , 87  abruptly reassume their initial width. The large section of the thus-formed funnel is directed towards the exterior of the enclosure  90  and the smaller section is inwardly-directed. The ratio of the length of the entrance to the channel  91  and of the smallest section of the funnel, on the one hand, and of the smallest section  91   a  and the length of the end of the channel  91  leading into the enclosure  90 , on the other hand, is about ⅔, ⅓. The purpose of this valve, whose channel  91  is divided into two parts, with their junction situated level with the smallest section of the funnel  91   a,  in the case of an enclosure for packaging a liquid, is to enable the drinking straw to be partly withdrawn above the level of the section  91   a  so it is left in the upper part of the channel  91 , the lower part of the channel  91  closing even though the drinking straw is engaged in the upper part of the channel  91 . Of course, this valve can be used in all of the previous embodiments designed for packaging liquids. The straw could also be replaced by a filling head, in particular for the packaging of liquid products other than beverages.  
         [0066]    All of the previous embodiments have a cut-out  32 , 41  provided in the fold of the sheet between the parallel welds  30 , 31  or  43 , 44 , etc. defining the valve channel. As a variation, in particular of the embodiments of FIGS. 20 and 21 where the valve is made in a material different to that of the enclosure walls, for the valve a very thin film can be used, which is not cut out or not pre-cut in a fold of the film, and is made of a material having elastomeric properties and a sufficient elasticity whereby it is not deformed in a non-elastic manner by the constraint resulting from placing the drinking straw in the channel, and is perforable by the drinking straw when it reaches the non-pierced bottom of the channel. Such a film can be made of polylefins such as terpolymers including ethylene, propylene and long-charrier dienic such as HIFAX XTR®, TECLAR®, ROYALENE® or TREFSIN®.  
         [0067]    All of the described embodiments can be made from endless lengths of sheet material or films until sealed enclosures are obtained and can then be separated from one another. An advantage of this manufacturing method resides in the fact that the formation of the valve and the formation of the enclosure with two or four walls are both obtained by longitudinal folding and/or welding as the sheet material advances. Due to this, once the valve has been formed, if it is in another sheet material than that of the enclosure itself, it is integrated into the enclosure without previously being cut. This avoids having to position the valve, which is a complex operation that slows down the production rate and necessitates costly investments.  
         [0068]    [0068]FIG. 25 illustrates a method of manufacturing a sealed enclosure shown in cross-section in FIG. 26. This method is carried out continuously starting from two films  92  and  93  that are unrolled and folded and welded as they advance. The different steps of the method are illustrated by different cross-sections of the sheet materials, seen in perspective. However, it is emphasized that these cross-sections are given only to illustrate the various operations carried out, and the sheet materials are only cut when the sealed enclosure is completed. Firstly, one can see the film  92  for forming the valve. This film  92  is firstly folded longitudinally into two parts  92   a,   92   b,  of unequal width. These two parts are welded by two longitudinal welds  94  which are interrupted between two parallel oblique welds  95  for forming the valve&#39;s channel. In the following step, a cut-out  96  is made in the fold of sheet  92  between the two oblique welds  95 .  
         [0069]    The second film  93  for forming the sealed enclosure is unrolled in the next step, alongside the edge of the part  92   a  of the valve formed in film  92 . A separator guide  97  is placed in the trajectory of film  92  and is arranged to be inserted between the parts  92   a,   92   b.  This separator  97  is arranged to allow the welding of the edge of the part  92   a  with the edge of film  93  without the part  92   b  being welded therewith.  
         [0070]    In the following steps, the film  93  is formed to provide the enclosure  98  illustrated in cross-section by FIG. 26, with two lateral bellows-like folded parts  99 . Lastly, the second longitudinal edge of film  93  is welded to the part  92   b  of film  92 , after having folded their two longitudinal edges by 90°. Hence, this sealed enclosure has an access to the inlet of the channel formed between the two oblique welds  95  situated on a large face of the enclosure and not in the edge thereof, as was the case up to now.  
         [0071]    The variation illustrated by FIGS. 27 and 28 concerns a manufacturing method with which is associated a unit for filling the enclosure with a liquid product to be packaged in this enclosure. As in the previous example, one starts from two films  100 , 101  respectively to make the valve  102  in the same manner as before, by folding unequal widths  100   a,   100   b,  the edge of the part  100   a  being welded to one edge of the film  101 .  
         [0072]    Then, the film  101  with valve  102  is made into a tubular shape about a filling hopper  103 , and a longitudinal weld  104  (FIG. 28) is made between the edge of part  100   b  and the other edge of film  101 , hence closing the tubular element formed about hopper  103 . Transverse welds  105  are provided with a regular spacing as the tubular element moves forward. Between two transverse welds  105  a metered amount of a product to be packaged is poured into the hopper  103  and the thusfilled sachets are separated from one another along the middle of the width of the transverse welds  105 .  
         [0073]    [0073]FIGS. 29, 30, illustrate yet another method of manufacturing a sealed enclosure which is differentiated from the previously-described embodiments by the fact that access to the channel  106  of valve  106  is via an opening  108  cut in a film  109  adapted to form a wall of the sealed sachet. As shown in FIG. 29, instead of forming the valve by folding a sheet, the same result can be obtained by welding the adjacent longitudinal edges of two strips  110 , 111  of unequal width. These two embodiments of the valve are interchangeable and are at the choice of the manufacturer. Next, as can be seen from FIG. 29, the free edge of strip  118  is welded to the inner face of film  109 , using a separator guide  112 , then the free edge of the strip  111  is welded to the same inner face of the film  109  using another separator guide  113 . The two free edges of the respective strips  110  and  111  are welded together on either side of the opening  108  hence allowing access to the channel  106  of valve  107 . Finally, a film  114  is unwound and welded to the two longitudinal edges of film  109 . Next, as in all of the preceding embodiments, the entire set of superimposed films (which in the example are only welded longitudinally with the exception of the channel  106 ) are welded transversally and cut along the middle of the width of the transverse weld to separate the sachets.  
         [0074]    In the various embodiments of the method according to the invention described above, when it is desired to weld together not the entire thickness of all of the superimposed sheets but only some of these sheets, a separator is inserted between the films, made of a material that is non-weldable with the sheet material. As a variation, the separator may be replaced by a heat resistant varnish applied to the reverse side of a film whose front side is to be welded, whereby this varnish matches the shape of the weld or welds to be made on the side to be welded. In this manner, welding of the valve can be done at the same time as welding of this valve to the film forming the walls of the sealed sachet, by coating the film of the valve with a varnish at the place where the valve-forming welds are made. By way of example, the heat resistant varnish could be a polyurethane varnish or an acrylic varnish.  
         [0075]    [0075]FIG. 31 shows a variation of the sealed sachet illustrated in FIG. 5. In this variation, the film  24  forming the valve  24   a,   24   b  is provided with a cut-away opening  115  obtained by a tongue  116  which is partly welded or stuck to the film  24  to hermetically close the opening  115 . By grasping the non-welded part of the tongue  116 , it can be pulled off to deflate the sachet.  
         [0076]    This sachet also includes a flap  117  welded to the edge  36  and forming a pocket to receive a postal identification slip. This flap  117  normally covers the tongue  116  and adheres to the sheet  26  hence avoiding this tongue being pulled off unwantedly.  
         [0077]    Lastly, FIG. 32 shows a final variation of the sealed enclosure in which the enclosure is formed of two films  118 , 119 , the film  118  being folded to form one of the parts  118   a  of the valve, whose other part is formed by a film  120  welded like all of the previous valves to the part  118   a.  Finally, the free edge of the film  120  is welded to the adjacent edge of film  119 . Thus, it has been demonstrated that: the valve can be integrated in a wall of the sealed enclosure as in the case of FIGS.  1  to  19 ; the valve can be made from a film which is separate from that of the sealed enclosure as in the case of FIG. 20; the valve can be made of a film welded to a folded film which is a wall of the sachet. In all of these cases, the valve is made continuously with the sealed enclosure and hence extends across the sachet between two opposite edges of this sealed enclosure.  
         [0078]    It is obvious to the person skilled in the art that the above-described enclosure with its fluid-tight closure valve can be made with other types of machine and that other embodiments are possible within the scope of the invention defined by the claims.