Abstract:
A double dispensing container including an outer container and an inner container, each container including a body and a head provided with a neck and a shoulder linking the neck to the body, the neck having a side wall and one or more dispensing orifices, the neck of the inner container being housed inside the neck of the outer container and having a section such that it provides one of more outflow passages for a pasty product A and, in combination with the inner surface of the outer container neck, one or more outflow passages for a pasty product B emerging onto a single or multiple orifice dispensing the product B. The inner neck is extended by a summit portion which is linked to the inner neck via a thin annular zone and which closes the single or multiple orifice dispensing product A.

Description:
FIELD OF THE INVENTION 
     The invention concerns packaging with several recipients provided with dispensing necks adjacent or placed side by side and used for storing and distributing different liquid, viscous, creamy or pasty products simultaneously (these products will henceforward be referred to as “pasty”). In particular, it concerns flexible tubes known as “multiple” tubes. Such packaging is used to store products separately from each other and to dispense them simultaneously via openings that are close together and, if possible, side by side, for example with a view to preparing a magisterial (or extemporaneous) prescription of a pharmaceutical product in a particular dosage form that is not commercially available, or with a view to preparing an adhesive from polymerizing agents, typically a cyanoacrylate, or with a view to preparing a chemically unstable cosmetic product, such as hair dye (a mixture of an oxidizing agent and a precursor), or, finally, simply with a view to providing a pleasant, amusing visual aspect when simultaneously dispensing pasty products of different colors (hair gels, toothpaste, etc.). 
     DESCRIPTION OF RELATED ART 
     While single, separate recipients enable products to be kept intact before mixing, the point of having a multiple recipient is to facilitate package management by being certain, at any time, of having available all the constituent parts of the mixture to be made, and to make it easier to make said mixture. Another advantage, which has appeared over the last few years, is related to the pleasant and amusing visual effect of pasty products of different colors simultaneously coming out of neighboring openings. 
     Whether for an extemporaneous preparation or for a simple visual effect, the aim is to keep the different products contained in the multiple recipient isolated from each other until they are first used and, if possible, to continue to ensure perfect leak-tightness between these products after said first use. To illustrate the multiple recipients concerned by the invention, we shall describe multiple flexible tubes and, more specifically, double tubes. 
     A multiple flexible tube comprises a head with a multiple-opening neck, connected to an external flexible skirt via a shoulder. The tube may comprise several concentric skirts, the products being contained either in the inner volume of the tube itself, or between the walls of the tube skirt and that of the tube which immediately surrounds the previous tube. In general, these are double tubes, comprising an inside and an outside tube. Such multiple tubes are described in patent applications EP 0 561 719, WO 00/63112 and WO 00/6311, in which the inside tube is fitted into the outside tube. 
     Recently, other double tubes have been described, in which a single, flexible skirt forms the outer envelope of the multiple tube. At least one transverse wall separates the compartments in the inside volume bounded by the skirt, said compartments being designed to contain different products. Multiple tubes are described, for example, in application WO 00/55602. 
     The present invention more specifically concerns the first type of multiple tube in which the tubes are produced separately and then assembled like a nest of dolls, each tube, with the exception of the smallest, encasing a tube of smaller dimensions (the dimensions involved being at least the skirt diameter and the neck diameter). It can also apply to the second type of tube, even though the leak-tightness problem described below is less important, as this second type of double tube is of necessity obtained by molding a dispensing head with a complex shape and with multiple openings, the bulk of the difficulty here having to do with obtaining a leak-tight connection for the head, not only with the outside cylindrical skirt, but also with the internal separating wall. 
     In patent application FR 1 209 359, the “self-mixing” tube comprises three tubes with a neck closed by a top wall, each fitted into the others and held concentrically in relation to each other by their respective necks. As long as the tube is not open, the products conditioned in the three separate envelopes formed in this way are correctly isolated. The self-mixing tube is opened in a single operation by simultaneously perforating or cutting the walls of the three tubes at an appropriate point. 
     The tubes described in application WO 00/12309 are obtained in the following way:
         a) an outside tube and an inside tube are made separately, the neck of the latter, having a complex shape, being designed so that it provides one or more flow paths for pasty product A that is to be contained in the inner tube and, in conjunction with the inside of the cylindrical wall of the neck of the outer tube, one or more flow paths for pasty product B that is to be contained between the inner tube and the outer tube, once these have been assembled;   b) the inner tube is assembled by insertion into the outer tube, the inner tube being held in place inside the outer tube at the level of the base of the neck using complementary means of axial fixing, typically a rib/groove clipping system.   c) the internal volume of the inner tube is filled with pasty product A;   d) the volume between the wall of the inner tube and that of the outer tube is filled with pasty product B;   e) the multiple tube is sealed by means of a final weld, by compressing and raising to a high temperature the open end of the skirt of the inner tube and the open end of the skirt of the outer tube, preferably simultaneously.       

     Prior to this, the tubes are made using conventional techniques: the head of the outer (or inner) tube is molded, the sprue removed and fixed to the end of a skirt that will become the outer skirt (or inner skirt). When the head is molded and fixed to the end of the skirt simultaneously (the head is overmolded to the end of the skirt), the molding tool is preferably designed so that the excess plastic resulting from the injection molding process (the sprue) or from the compression molding process, is localized above the top part of the neck. This surplus material must be removed. As the neck is cylindrical, said surplus material is removed, advantageously for large production runs, by turning, generally on devices known as plugging machines, where tubes, placed on rotary chucks, undergo various operations such as sprue removal, lid fitting, closure screwing, etc. But this process has the drawback of not being very accurate in terms of the both the axial positioning and the perpendicularity of the sprue removal cut. Because of this it is not possible to have perfect control over the neck height of each of these tubes, specifically the distance between the mouth—the top part of the neck—and the means of axial fixing designed to work in conjunction with the complementary means of axial fixing of the other tube. The dispersion of these heights and the imperfect perpendicularity of the cut do not make it possible to obtain leak-tightness between the products during storage, even before they are used for the first time. Consideration was given to the idea of using leak-tight seals with a staggered profile to match the differences between the mouths of the inner and outer necks, but this solution proved to be of little worth, either technically or economically. 
     The applicant therefore attempted to obtain a double tube by assembling an inner and an outer tube made separately, said double tube making it possible to store two products separately and in a leak-tight manner, before and even after they are used for the first time. 
     SUMMARY OF THE INVENTION 
     A first subject according to the invention is a double dispensing recipient comprising an outer and an inner recipient, said inner recipient being designed to contain a pasty product A and being housed inside the outer recipient in such a way that the volume bounded by its outer surface and the inner surface of the outer recipient is to contain a pasty product B, each recipient comprising a body and a head provided with a neck and a shoulder connecting said neck to said body, said neck having a side wall and an open end provided with one or more dispensing openings, the neck of the inner recipient being housed inside the neck of the outer recipient and having a cross-section shaped so as to offer one or more flow paths for dispensing pasty product A and, in combination with the inner surface of the neck of the outer recipient, one or more flow paths for pasty product B leading to a single or multiple opening for dispensing product B, wherein the inner neck is extended by means of a top portion which is connected to said neck by a slender ring-shaped zone and which blocks the single or multiple dispensing opening of product A. 
     The double dispensing recipient, according to the invention, may be a double tube, comprising an outer tube and an inner tube housed inside the outer tube so that the volume bounded by the outer surface of the inner tube and the inner surface of the outer tube can contain a pasty product B different from the pasty product A contained within the inner tube. Each tube comprises a flexible skirt and a head provided with a neck and a shoulder connecting said neck to said flexible skirt. Each of the parts of the recipient or of the tube will be referred to as inner if it belongs to the inner tube, and outer if it belongs to the outer tube. 
     The inner neck is housed inside the outer neck. It has a cross-section shaped so that it offers one or more flow paths for pasty product A, leading to one or more dispensing openings. In combination with the inner surface of the neck of the outer recipient, the outer surface of the inner neck offers one or more flow paths for pasty product B leading to a single or multiple opening. The inner neck is covered by a top portion which is connected to said inner neck by a slender ring-shaped zone, i.e. less thick than that of the barrel of the inner neck and that of the top portion. This top portion closes the single or multiple dispensing opening of product A contained within the inner tube. 
     In a first embodiment of the invention, the top portion may, for example, be a single top wall which includes said slender ring-shaped zone, the outline of the latter bounding the desired shape of the opening or openings. The slender ring-shaped zone is a breakable area that comprises a notch, whose cross-section in a plane comprising the axis of the neck is turned in a direction that is substantially parallel with said axis. In such a geometrical layout, the top portion acting as a lid may be removed by exerting an axial force perpendicular to said top wall. 
     But in order to improve hermetic separation between product A and product B after they have been used for the first time, it is preferable to provide the inner neck with said top wall by locating the slender ring-shaped zone on the side wall of said inner neck, so that once burst, the open end of the inner neck systematically protrudes beyond the mouth of the outer neck, whatever the dispersions due to manufacturing tolerance. In such a case, the end of the inner neck is extended by means of a top portion connected to said inner neck by a slender ring-shaped zone located on the barrel of the neck and preferably notched so as to localize deformation until bursting occurs during first-time use. The inner head assembly, including the top portion can to advantage be molded in a single piece and the mold is designed so that the slender ring-shaped zone is accessible after the two tubes have been assembled: once the slender ring-shaped zone has been burst and the top portion detached, the open end of the inner neck protrudes slightly from the mouth of the outer neck, which makes it possible to provide, by means of a leak-tight seal placed on the cap, at the bottom of the screw thread, for example, hermetic separation between product A and B. 
     According to this method of the invention, slender ring-shaped zone is a breakable area which extends on the side wall from the inner neck with a notch whose cross-section in a plane comprising the axis of the inner neck is turned in a direction that is substantially perpendicular with said axis. In this case, the breakable zone is placed at a distance from the means of axial fixing (typically a rib clipping system) such that the breakable area is on the outside after assembly of the inner tube and the outer tube, i.e. it is “above” the mouth of the outer neck (the tube being conventionally presented vertically, with the head at the top). In this way, if a double tube is produced according to the process describes in WO 00/63112, the axial position of the breakable zone is defined by a certain distance from the rib clipping system located at the base of the inner neck; said distance has to be higher than the distance between the mouth of the outer neck and the clip-on groove of the outer neck 
     The top portion, acting as a lid, can be cleanly cut out using a cutting tool which is moved along the slender ring-shaped zone. The top portion can be made to move greatly in relation to the remainder of the inner neck, this large relative movement resulting in a large deformation located in the slender ring-shaped zone, which then bursts. If the top portion is provided with a grooved side wall or one that is polygonal in cross-section, preferably concave (star-shaped, for example), this can easily be made to rotate around the axis of the neck. One can thus impose on the top portion of the inner neck can thus be made to undergo a large rotation, while the remainder of the double tube is motionless. 
     Whatever the form of the inner neck, therefore, the top portion closing the inner (single or multiple) opening and separated from said inner neck by said breakable zone can have an arbitrary form appropriate to the application of a large movement (typically a rotation) which said top portion is made to undergo. 
     It may, for example, have a polygonal edge cross-section, that can easily be made to rotate. To tear this breakable zone the first time the recipient is used, the closure cap may be used, to avoid having to use of a special tool. This latter has, for example on the outer wall, following the example of the closure cap described in application EP 0 192 136, a housing of a shape that is complementary to that of the side wall of the top portion. This housing, once the cap has been turned through 180° in relation to its usual closing position, acts as a lock inside which the top portion of the inner neck is inserted, this acting as a key. The cap is turned around the axis of the neck, causing a tear located at the level of the slender ring-shaped zone and the top portion is detached from the neck. 
     Obviously, the key-lock functions can be reversed. The top wall has in this case a cavity bordered by a ribbed inner side wall or one with a polygonal cross-section, preferably concave, and the closure cap has a protuberance complementary in shape on its outer wall. 
     The outer neck can to advantage also be surmounted by a top portion which closes the multiple opening. This top portion is also connected to the outer neck via a slender or notched ring-shaped zone. Preferably, this top portion is hollow so that the top portion of the inner tube can be housed in its cavity. Preferably also, in the version in which the top portion is torn by rotation, the inner and outer surfaces of its side wall typically have a polygonal contour, typically star-shaped; for the first, this is complementary to the contour of the side wall of the top portion of the inner neck and, for the second, it is complementary to the contour of the inner surface of the cap. In this way, rotating the cap leads to bursting of the two breakable areas which connect the inner and outer top portions to their respective neck. 
     The invention has been described relative to double tubes and double containers. It can of course be applied to containers or multiple tubes designed to contain more than two different products. Another subject of the invention is therefore a multiple dispenser including an outer container, an inner container and n intermediate containers (n≧1), said inner container being designed to contain a pasty product A and being placed inside an intermediate container, itself placed, like a nest of dolls, inside an intermediate container of greater dimensions, the largest of these being placed inside the outer container, each container being placed inside the container that is immediately larger so that the volume bounded by its outer surface and the inner surface of said immediately larger container can contain a pasty product Bi (l=1 to n+1) separated from the other pasty products, each container including a body and a head provided with a neck and a shoulder connecting said neck to said body, said neck having a side wall and an open end provided with one or more dispensing openings, the neck of the inner container being housed inside the neck of the outer container and having a cross-section with a shape such as offers at least one flow path for pasty product A and, in combination with the inner surface of the neck of the immediately larger container, at least one flow path for pasty product Bi, wherein the inner neck is prolonged by a top portion which is connected to said inner neck by a slender ring-shaped zone which closes the single or multiple dispensing opening of product A. 
     As indicated above, for each inner container, the neck of the immediately larger container is, to advantage, also surmounted by a top portion, connected to the neck of said container via a slender and/or notched ring-shaped zone. Preferably, this latter top portion is hollow so that the top portion of the immediately smaller container can be housed in its cavity. 
     Said slender and/or notched ring-shaped zone is placed on the wall of the neck of said inner container so that, after assembly of said neck with that of the immediately larger container, followed by bursting of the slender and/or notched ring-shaped zone and detachment of said top portion, the open end of said neck is above the mouth of the neck of the immediately larger container, the tube being presented vertically, with the head at the top. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a ,  1   b ,  1   c ,  1   d  and  1   e  illustrate a first embodiment of the invention.  FIG. 1   a  shows a cross-section through a diametrical plan of the double tube with its closure cap before being used for the first time.  FIG. 1   b  represents the double tube as, using the cap turned upside down, the top portion, which acts as a lid on the opening of the inner neck, is removed.  FIG. 1   c  shows the double tube with its cap after having been used for the first time.  FIG. 1   d  shows an axonometric projection of the double tube without its cap, before removal of the top portion acting as a lid on the inner neck.  FIG. 1   e  shows the double tube without its cap in perspective, after removal of the top portion acting as a lid on the inner neck. 
         FIGS. 2   a ,  2   b ,  2   c ,  2   d  and  2   e  illustrate a second embodiment of the invention.  FIG. 2   a  shows a cross-section through a diametrical plan of the double tube with its closure cap before being used for the first time.  FIG. 2   b  shows the double tube as, using the cap turned upside down, the top portion, which acts as a lid on the opening of the inner neck, is removed.  FIG. 2   c  shows the double tube with its cap after having been used for the first time.  FIG. 2   d  shows an axonometric projection of the double tube without its cap, before removal of the top portion acting as a lid on the inner neck.  FIG. 2   e  shows the double tube without its cap in perspective, after removal of the top portion acting as a lid on the inner neck. 
         FIGS. 3   a ,  3   b ,  3   c  and  3   d  illustrate a third embodiment of the invention.  FIG. 3   a  shows a cross-section through a diametrical plan of the double tube with its closure cap before being used for the first time.  FIG. 3   b  shows the double tube as, using the cap turned upside down, the top portion, which acts as a lid on the opening of the inner neck, is removed.  FIG. 3   c  shows the double tube with its cap after having been used for the first time.  FIG. 3   d  illustrates the head of the inner tube in perspective, before removal of the top portion acting as a lid. 
         FIGS. 4   a ,  4   b  and  4   c  illustrate an improvement of the second embodiment of the invention in which, by means of the addition of a tamperproof strip, leak-tightness between the products after they have been used for the first time is improved.  FIG. 4   a  shows a cross-section through a diametrical plan of the double tube with its closure cap before being used for the first time.  FIG. 4   b  shows the double tube as, using the cap turned upside down, the top portion, which acts as a lid on the opening of the inner neck, is removed.  FIG. 4   c  shows the double tube with its cap after having been used for the first time. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Example 1 
     FIGS.  1   a ,  1   b ,  1   c ,  1   d  and  1   e    
       FIGS. 1   a  to  1   e  show a double tube  100 , including an outer tube  110  and an inner tube  120  housed inside the outer tube  110  so that the volume bounded by the outer surface  125  of the inner tube  120  and the inner surface  115  of the outer tube  110  can contain a pasty product B different from the pasty product A contained in the inner tube  120 . The inner tube  120  includes a flexible inner skirt  121  and an inner head  122  provided with an inner neck  123  and an inner shoulder  124  connecting said inner neck to said inner flexible skirt. The outer tube  110  comprises a flexible skirt  111  and an outer head  112  provided with an outer neck  113  and an outer shoulder  114  connecting said outer neck to said outer flexible skirt. Shoulder  114  is provided with an insert  170  made of PBT (polybutylene terephthalate) which acts as an efficient barrier to odors 
     The inner neck  123  is housed inside the outer neck  113 . Its cross-section is clover leaf shaped here, such as is illustrated in application WO 00/63111 (but here with three leaves instead of four). It provides a central flow path (with a clover leaf cross-section) for pasty product A and, in combination with the cylindrical surface of the outer neck, three peripheral flow paths for the pasty product B. 
     The end of the inner neck  123  which surrounds the dispensing opening of the pasty product A is prolonged by a top portion  126  connected to said inner neck by a breakable intermediate zone  127  having a ring-shaped notch  128  whose cross-section in a plane comprising axis  160  is turned in a substantially perpendicular direction to said axis. 
     The top portion  126  is provided with a side wall  129  which extends the barrel of the inner neck whose cross-section, in the form of a clover leaf, is substantially polygonal concave. This can be easily made to rotate around axis  160 . 
     The slender ring-shaped zone  127  is placed on the side wall of the inner neck  123  so that after assembly of the inner neck and the outer neck, it is on the outer surface of the double tube, i.e. it is “above” the mouth  1130  of the outer neck  113  (the tube being conventionally presented vertically, with the head at the top). When molding the head of the inner tube, the axial position of the slender ring-shaped zone is defined by a certain distance from the clipping system rib  1231  located at the base of the inner neck  123 , said distance being greater than the distance between mouth  1130  and clipping system groove  1131  of outer neck  113 . 
     To tear this breakable area when being used for the first time, closure cap  150  is used. The latter has a housing  151  of shape complementary to that of the side wall  129  of the top portion  126 . This housing, once the cap has been turned over through 180° ( FIG. 1   b ) in relation to its usual closing position ( FIGS. 1   a  and  1   e ), acts as a lock inside which the top portion  126  of the inner neck  123 , which acts as a key, is inserted. The cap  150  is turned around the axis  160 , causing a tear located at the level of the slender ring-shaped zone  127  and the top portion is detached from the neck. 
     Example 2 
     FIGS.  2   a ,  2   b ,  2   c ,  2   d  and  2   e    
       FIGS. 2   a  to  2   e  show a double tube  200 , including an outer tube  210  and an inner tube  220  housed inside the outer tube  210  so that the volume bounded by the outer surface  225  of the inner tube  220  and the inner surface  215  of the outer tube  210  can contain a pasty product B different from the pasty product A contained in the inner tube  220 . The inner tube  220  includes a flexible inner skirt  221  and an inner head  222  provided with an inner neck  223  and an inner shoulder  224  connecting said inner neck to said inner flexible skirt. The outer tube  210  comprises a flexible skirt  211  and an outer head  212  provided with an outer neck  213  and an outer shoulder  214  connecting said outer neck to said outer flexible skirt. Shoulder  214  is provided with an insert  270  made of PBT which acts as an efficient barrier to odors. 
     The inner neck  223  is placed inside the outer neck  213 . It is here circular in cross-section and is provided with three radial ribs  230  regularly distributed on its outer surface. It provides a central flow path with circular cross-section for pasty product A and, in combination with the cylindrical surface of the outer neck, three peripheral flow paths for pasty product B. 
     The end of the inner neck  223  which surrounds the dispensing opening for pasty product A is extended by a top portion  226  connected to said inner neck by a breakable intermediate zone  227  having a ring-shaped notch  228  whose cross-section in a plane comprising axis  260  is turned in a substantially perpendicular direction to said axis. 
     The top portion  226  is provided with a grooved side wall  229  that can easily be made to rotate around axis  260 . To tear this breakable area when using for the first time, closure cap  250  is used. This has a hollow, ribbed housing  251  of complementary shape to that of the side wall  219  of the top portion  216  of outer neck  213 . This top portion  216  is connected to outer neck  213  via a notched ring-shaped area  217 . The top portion  216  is hollow so that the top portion  226  of the inner tube can be placed in its cavity. The inner and outer surfaces of the side wall  219  are provided with ribs, giving a relief that is complementary to the contour of the side wall  229  of the inner top portion  226  and to the contour of the hollow housing  251  of closure cap  250  respectively, to ensure that the inner  229  and outer  219  top portions are made to rotate relatively and simultaneously. 
     The notched ring-shaped zone  227  is placed on the side wall of the inner neck  223  so that after assembly of the inner neck and the outer neck, it is “above” the mouth  2130  of the outer neck  213  (the tube being conventionally presented vertically, with the head at the top). When molding the head of the inner tube, the axial position of the slender ring-shaped zone is defined by a certain distance from the clipping system rib  2231  located at the base of the inner neck  223 , said distance being greater than the distance between mouth  2130  and clipping system groove  2131  of outer neck  213 . 
     Once cap  250  has been turned through 180°, hollow housing  250  acts as a lock inside which the top portion  216  of the outer neck  213 , which acts as a key, is inserted. Cap  250  is turned around axis  260 , causing a tear located at the level of the notched breakable ring-shaped zone  217  and another tear at the level of the notched breakable ring-shaped zone  227   
     Example 3 
     FIGS.  3   a ,  3   b ,  3   c  and  3   d    
       FIGS. 3   a  to  3   d  show a double tube  300 , including an outer tube  310  and an inner tube  320  housed inside the outer tube  310  so that the volume bounded by the outer surface  325  of the inner tube  320  and the inner surface  315  of the outer tube  310  can contain a pasty product B different from the pasty product A contained in the inner tube  320 . The inner tube  320  includes a flexible inner skirt  321  and an inner head  322  provided with an inner neck  323  and an inner shoulder  324  connecting said inner neck to said inner flexible skirt. The outer tube  310  comprises a flexible skirt  311  and an outer head  312  provided with an outer neck  313  and an outer shoulder  314  connecting said outer neck to said outer flexible skirt. Shoulder  314  is provided with an insert  370  made of PBT which acts as an efficient barrier to odors 
     The inner neck  323  is placed inside the outer neck  313 . It is here circular in cross-section and is provided with three radial ribs  330  regularly distributed on its outer surface. It provides a central flow path with circular cross-section for pasty product A and, in combination with the cylindrical surface of the outer neck, three peripheral flow paths for pasty product B. 
     The end of the inner neck  323  which surrounds the dispensing opening of the pasty product A is prolonged by a top portion  326  connected to said inner neck by a breakable zone  327  having a ring-shaped notch  328  whose cross-section in a plane comprising axis  360  is turned in a substantially perpendicular direction to said axis. 
     The top portion  326  is provided with an inner ribbed side wall  329  that can easily be made to rotate around axis  360 . To tear the breakable area  327  when using for the first time, closure cap  350  is used. This has a protuberance  351  complementary in shape to that of the inner side wall  329  of the top portion  326 . Once the cap has been turned through 180° ( FIG. 3   b ) in relation to its usual sealing position ( FIGS. 3   a  and  3   c ), this protuberance acts as a key which is inserted into the cavity of the top portion  326  of the inner neck  323 , this cavity being bounded by the inner ribbed side wall  329  which acts as a lock. The cap  350  is turned around the axis  360 , causing a tear located at the level of the slender ring-shaped zone  327  and the top portion is detached from the neck. 
     The slender ring-shaped zone  327  is placed on the side wall of the inner neck  323  so that after assembly of the inner neck and the outer neck, it is on the surface outer of the double tube, i.e. it is “above” the mouth  3130  of the outer neck  313 . When molding the head of the inner tube, the axial position of the slender ring-shaped zone is defined by a certain distance from the clipping system rib  3231  located at the base of the inner neck  323 , said distance being higher than the distance between mouth  3130  and the clipping system groove  3131  of the outer neck  313 . 
     A layout of this kind makes it possible to decrease the volume occupied before bursting by the top portion of the inner neck which is above the neck with the multiple opening. The cap can also be provided with a leak-tight seal  380  which, only slightly compressed during storage before being used for the first time ( FIG. 3   a ) because of the compactness of said top portion, can easily regain its initial shape and thereby continue to act as a leak-tight seal after said top portion ( FIG. 3   c ) has burst. 
     Example 4 
     FIGS.  4   a ,  4   b , and  4   c    
       FIGS. 4   a  to  4   c  show an alternative to the double tube shown in example 2, where, through the addition of a strip  453  in the continuation of the opening end of side skirt  452  of cap  450 , sealing between products after top portions  416  and  426  have been simultaneously opened when used for the first time, can be significantly improved. 
     When being used for the first time, the strip  453 —which can, for example be, used as a tamperproof device—is torn along the ring-shaped bursting zone  457  and cap  450  is turned through 180° ( FIG. 4   b ) to remove the top wall  426  of the inner tube and that  416  of the outer tube, by rotation. The open end of the skirt arrives, in closed position, near shoulder  414  of the tube head. The height of strip  453  is substantially equal to that of the top portion  416  of the outer tube, which is above the notched ring-shaped breakable area  417 , so that, when cap  450  is once again turned through 180° to close the opening, the leak-tight seal  480  comes in contact with the mouth  4230  of the inner neck  423  and  4130  of the outer neck  413 . 
     Double tube  400  includes an outer tube  410  and an inner tube  420  housed inside the outer tube  410  so that the volume bounded by the outer surface  425  of the inner tube  420  and the inner surface  415  of the outer tube  410  can contain a pasty product B different from the pasty product A contained in the inner tube  420 . 
     The inner tube  420  includes a flexible inner skirt  421  and an inner head  422  provided with an inner neck  423  and an inner shoulder  424  connecting said inner neck to said inner flexible skirt. The outer tube  410  comprises a flexible skirt  411  and an outer head  412  provided with an outer neck  413  and an outer shoulder  414  connecting said outer neck to said outer flexible skirt. Shoulder  414  is provided with an insert  470  made of PBT which acts as an efficient barrier to odors. 
     The end of inner neck  423  which surrounds the dispensing opening of pasty product A is prolonged by a top portion  426  connected to said inner neck by a breakable intermediate zone  427 . The top portion  426  is provided with a grooved side wall  429  that can easily be made to rotate. To tear this breakable area when using for the first time, closure cap  450  is used. This has a hollow, ribbed housing  451  of complementary shape to that of the side wall  419  of the top portion  416  of outer neck  413 . This top portion  416  is connected to outer neck  413  via a notched ring-shaped area  417 . The top portion  416  is hollow so that the top portion  426  of the inner tube can be housed in its cavity. The inner and outer surfaces of the side wall  419  are provided with ribs, giving a relief that is complementary to the contour of the side wall  429  of the inner top portion  426  and to the contour of the hollow housing  451  of closure cap  450  respectively, to ensure that the inner  429  and outer  419  top portions are made to rotate relatively and simultaneously. 
     The slender ring-shaped zone  427  is placed on the side wall of the inner neck  423  so that after assembly of the inner neck and the outer neck, it is on the outer surface of the double tube, i.e. it is “above” the mouth  4130  of the outer neck  413 . When molding the head of the inner tube, the axial position of the slender ring-shaped zone is defined by its distance from the clipping system rib of the inner neck  423 , which must be greater than the distance between mouth  4130  and the clipping system groove of the outer neck  413 . 
     Once cap  450  has been turned through 180°, hollow housing  451  acts as a lock inside which the top portion  416  of the outer neck  413 , which acts as a key, is inserted. Closure cap  450  is turned around the axis, causing a tear located at the level of the notched breakable ring-shaped zone  417  and another tear at the level of the notched breakable ring-shaped zone  427 . As the mouth  4230  of the inner neck  423  remains above mouth  4130  of the outer neck  413 , the leak-tight seal  480  first comes into contact with the inner mouth  4230  to ensure leak-tightness between products. This leak-tight seal  480  is made from an elastomer. It is flexible and thick enough to also come into contact with the outer mouth  4130  and to ensure that the products are properly sealed in relation to the outside. 
     In the example illustrated, hollow ribbed housing  451  has a shape that is complementary and very similar to that of the side wall  419  of the top portion  416  of the outer neck  413 , so that after the breakable zone  417  has burst, said top portion remains trapped in said hollow housing, acting as proof that the recipient has been used for the first time. Similarly, the top portion  426  of the inner tube can also remain trapped in the hollow of the top portion  416  of the outer tube.