Abstract:
The two-component cartridge comprises an outer container ( 10 ) and an inner container ( 20 ) coaxially arranged therein. The inner container ( 20 ) comprises a bellows-type section ( 21 ) adapted to be folded like an accordion. The rear end of the bellows-type section ( 21 ) is inserted into a piston ( 32 ). In the folded condition, the bellows-type section is accommodated in an annular space ( 41 ) of the piston ( 32 ). The piston ( 32 ) comprises an annular piston breast ( 34 ) and a central piston breast ( 37 ) arranged at the same level. The invention allows easy filling of the two-component cartridge from the rear side and almost complete evacuation. The two-component cartridge can be evacuated by means of the same tool as is used for a common cartridge containing only a single material.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a two-component cartridge, in particular a cartridge for discharging components of adhesives or foamed materials which are intended to get in contact with each other not before having been discharged, for the purpose of being mixed such that they react on each other. 
     Numerous solutions are known for two-component cartridges where the two components are stored separately from each other and are discharged at the same time and mixed with each other. In this connection a distinction is generally made between a coaxial cartridge and a biaxial cartridge. In the case of a coaxial cartridge an inner container is coaxially arranged inside an outer container. For simultaneous discharge of the two components by means of a commercially available standard evacuating means destined for a one-component cartridge an additional evacuating tool is required which comprises an inner mandrel and an annular mandrel of great length. When such a coaxial cartridge is used in connection with a conventional evacuating tool, said cartridge may have only half the length of a common cartridge because of the length of the required evacuating tool. In the case of biaxial two-component cartridges two containers each having a separate piston are arranged side by side. Here, a complex evacuating tool is needed. This solution requires high evacuating forces. 
     From DE-OS 2 007 199 an evacuating device for liquid cosmetic products is known where the one component is contained in an inner container and the other component is contained in an outer container. The inner container is adapted to fold like an accordion and its rear end is fastened to a piston which is displaceably arranged in the outer container. When the piston is advanced, the component contained in the outer container is moved in forward direction and the component contained in the inner container is also discharged because of the reduced volume of the inner container. According to another solution the piston comprises an annular space in which a knife is disposed which cuts up the cylindrical wall of the inner container when the piston is advanced in order to provide space for further advancement of the piston. 
     From DE 29 39 116 A1 a two-component cartridge is known which comprises an outer container, an inner container coaxially arranged therein and configured as a bellows-type section, and a piston displaceably arranged in the outer container. The piston is provided with a recess whose bottom supports the inner container. For displacing the piston the inner container is folded and received by the recess of the piston. The inner container is configured as a bag which is closed at the rear end by the bottom of the bag. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a two-component cartridge for flowable media, which is easy to fill with the two components being kept separate from each other, and allows residual discharge of the two components. 
     In the two-component cartridge according to the invention the inner container comprises at its rear end a filling opening which is open at first and is closed by the piston when the material has been filled in. The piston comprises a projection axially extending into the inner container, said projection forming a central piston breast. The function of the piston projection is, on the one hand, that its central piston breast ensures maximum residual discharge of the component in the inner container, and on the other hand, that it forms a mandrel for ordered accommodation of the inner container when the latter is folded. 
     The two-component cartridge according to the invention can be evacuated using a commercially available standard evacuating means destined for one-component cartridges. 
     Good filling capability of the cartridge results from the fact that prior to placement of the piston both the inner container and the outer container are open at the rear end such that the two materials can be pressed into the respective filling opening. The materials can be pressed in simultaneously or one after the other. 
     Preferably, the projection provided on the piston forms, together with a recess of the piston and/or together with a constricted portion of the outer container, an annular space which receives the folded inner container when the piston is in the advanced position. This promotes the ordered folding of the inner container, and consequently an extremely small amount of residue of the corresponding component remains in the container. 
     The two-component cartridge according to the invention offers the possibility to accommodate the hazardous component of the two component materials in the inner container since the latter offers a residual evacuation capability. When the cartridges have been emptied, there is no danger that persons get in contact with a residue of the hazardous component which has not yet reacted. In the case of conventional coaxial cartridges it is however possible that the container wall shows fissure-type leaky areas and resultant leakage and adhesion of residues. The annular space receiving the folded inner container also reduces the amount of residue and forces the inner container into the form provided for the compressed condition. 
     According to a preferred embodiment of the invention it is provided that the piston comprises two separate piston portions of which a first piston portion comprises the first piston breast and a second piston portion comprises the second piston breast, and that one of the piston portions has a supporting surface for supporting and advancing the other piston portion. This allows the two containers to be filled one after the other and the filled container to be closed by inserting the respective piston portion. This prevents the two components from unintentionally getting into contact with each other. During the evacuation process the pressure is directly exerted only on one of the piston portions, and this piston portion supports and advances the other piston portion. 
     Each piston portion may comprise a piston edge supported on the wall of the outer container. In this way each piston portion is individually centered in the outer container. 
     The inner container is preferably configured as a bellows-type section being corrugatedly folded. The inner container is self-supporting and dimensionally stable. It is plastically deformable. For these requirements a metal is suited, in particular aluminum or an aluminum alloy. Aluminum offers the advantage that it has good plastic deformation characteristics. It has turned out that a bellows-type section of thin-walled aluminum is excellently suited as inner container. 
    
    
     Hereunder an embodiment of the invention is explained in detail with reference to the drawings in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a longitudinal section of a first embodiment of the two-component cartridge in the filled condition, 
     FIG. 2 shows a longitudinal section of the first embodiment in the evacuated condition, 
     FIG. 3 shows longitudinal section of the first piston portion, 
     FIG. 4 shows a longitudinal section of the second piston portion, 
     FIG. 5 shows a part-sectional view of the inner container, 
     FIG. 6 shows a longitudinal section of a second embodiment of the two-component cartridge in the filled condition, and 
     FIG. 7 shows a longitudinal section of the second embodiment in the evacuated condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The two-component cartridge shown in FIGS. 1-5 is adapted to accommodate flowable materials, in particular components of adhesives or foamed materials. It comprises an outer container  10  having an elongate cylindrical cartridge body  11  of plastic material. The outer container  10  is closed at its front end  12  by a front wall  13  from which a outlet channel  14  extends. Said outlet channel is closed by an integral cap  15  which can be removed at a circumferential annular groove  16 . The rear end  17  of the outer container  10  is open. 
     In the outer container  10  the inner container  20  is coaxially arranged. The latter comprises an essentially cylindrical bellows-type section  21  of aluminum. At the front end  22  of the bellows-type section  21  a container breast  23  is provided from which an inner outlet channel  24  extends coaxially in the outer outlet channel  14 . The inner outlet channel  24  may comprise a separating film  25  adapted to be pushed open. 
     On the outside of the tubular outlet channel  24  circumferential sawtooth ribs  26  are arranged which are squeezed into longitudinal webs  27  on the inside of the outer outlet channel  14 . The ribs  26  allow insertion of the inner outlet channel  24  into the outer outlet channel  14  but prevent it from being retracted. The inner outlet channel  24  is centered in the outer outlet channel  14  and thus the front end  22  of the inner container  20  is centered relatively to the outer container  10 . 
     On the outside of the container breast  23  ribs  28  are provided which hold the container breast  23  at a distance to the front wall  13 . At the rear end of the inner container  20  circumferential beads  46  are located which sealingly engage the inner surface of the one annular piston portion  33 , and therebehind a filling opening  52  (FIG. 5) is provided which is later closed by the piston  32 . 
     Between the inner container  20  and the outer container  10  an annular space  30  is provided which receives the first component. The space  31  inside the inner container  20  receives the second component. 
     The rear end  17  of the outer container  10  is closed by a piston  32 . Said piston comprises a first piston portion  33  having an annular piston breast  34  and a circumferential piston edge  35  pressing against the inside of the outer container, and a second piston portion  36  having a central piston breast  37  and a piston edge  38  also pressing against the inside of the outer container  10 . The piston  32  comprises a projection which is open from the rear end. The second piston breast  37  is located at the projection  39  of the piston portion  36 , which extends into the open end of the inner container  20 . It is disposed approximately at the same level as the outer piston breast  34 . The projection  39  coaxially extends into a recess  40  of the piston portion  33 . Between the projection  39  and the recess  40  an annular space  41  is provided which can receive the folded inner container  20 . 
     Behind the annular space  41  a narrowed insertion zone  42  is located in which a constricted section  43  of the first piston portion  33  is provided with circumferential ribs  44  directed towards the inside, said ribs  44  pressing against the rear end of the cylindrical area of the inner container  20 . In this area the inner container  20  is provided with beads  46  directed towards the inside (FIG.  5 ), which are located between the ribs  44  and pressing against the outer surface of the projection  39 . 
     The piston portion  36  comprises at its rear end a bend  56  extending via a collar  47  directed towards the front and another bend  48  into the piston edge  38  directed towards the rear. At the bend  56  the piston portion  39  forms a pocket  49  into which extends the rear end of the piston portion  33  and where it is supported by a supporting surface  50 , namely the inner surface of the bend  56 . In the bend  48  small openings  51  are provided which allow perfect venting when the piston is placed. 
     First, the empty inner container  20  is fixed in the outer container  10  by centering the inner outlet channel  24  in the outer outlet channel  14 . The inner container  20  is dimensionally stable and cannot be radially expanded by the internal pressure produced during the filling process. 
     The two components are filled in successively from the rear end  17 , wherein the piston  32  is not yet placed. Optionally, the one or the other component can be filled in first. Preferably, the annular space  30  is filled first. Then the piston portion  33  is placed in position, wherein the air can escape from below the circumferential ribs  44 . Then the space  31  is filled with the other component, and finally the second piston portion  36  is placed in position, whereby the rear end  17  of the cartridge is closed. In this condition shown in FIG. 1 the cartridge is supplied to the user. 
     During the evacuation process the advancing disk of an evacuating tool presses against the rear end of the piston  32 , whereby the two piston portions  33  and  36  are advanced to the same extent. During this process the inner container  20  folds like an accordion. The bellows-type section is configured with an corrugating folding such that the folding process proceeds from rear to front. The corrugation of the bellows-type section is selected such that the bellows-type section, in the folded condition, gets jammed in the annular gap  41  and sealingly fills the latter. At the end of the advance movement the bellowstype section in its folded condition is, according to FIG. 2, completely accommodated in the annular space  41 . The first piston breast  34  matches the inside of the front wall  13 , and the second piston breast  37  matches the container breast  23  of the inner container. In the completely advanced condition the piston breast  37  abuts on the container breast  23 , and the piston breast  34  abuts on the front wall  13 . Thus both spaces are almost completely evacuated. 
     For detection of the existing residue in the cartridge at each stage, the outer container  10  is at least partly made from a translucent material. On the outside a scale indicating the respective state of evacuation on the basis of the piston position is provided. The position of the piston  32  can be seen through the cartridge wall. 
     The embodiment shown in FIGS. 6 and 7 essentially corresponds to the first embodiment such that the following description is limited to the explanation of the differences. In the second embodiment the piston  32   a  comprises a single piston portion. It is provided with the projection  39  extending into the rear end of the inner container  20 , with an insertion zone  42  being formed at the rear end of the projection  39 . At the rear end the projection  39  passes via a bend  56  into a collar  47  directed towards the front, which is joined by the outer annular piston breast  34 . Said annular piston breast  34  is arranged at a position much more at the rear than the central piston breast  37 . 
     At the front end the cylindrical outer container  10  comprises a constricted portion  60 . In the area of said constricted portion the cylinder wall has a smaller diameter than in the remaining area of the cartridge body  11 . The constricted portion  60  is defined by a shoulder  61 . In the area of the constricted portion  60  longitudinal ribs  62  may be provided. The length of the constricted portion  60  is equal to the length of the area of the projection  39  protruding beyond the piston breast  34  such that in the evacuation condition shown in FIG. 7 the central piston breast  37  abuts on the container breast  23  of the inner container, while the annular piston breast  34  bears against the shoulder  61 . Between the constricted portion  60  and the projection  39  the annular space  41  is formed which receives the compressed bellows-type section  21 . 
     In the second embodiment, too, the inner container and the outer container are first filled with the respective component, wherein the two components are strictly separated from each other. After the filling process the piston  32   a  is placed and, in the insertion zone  42 , the rear end of the inner container  20  is inserted from both sides into the piston. Since the projection  39  is first immersed into the inner container and closes the latter, it is reliably prevented that the two components unintentionally get in contact with each other during placement of the piston. Here, too, folding of the bellows-type section  21  is effected from the rear end and proceeds towards the front, wherein the folded bellows-type section is received by the projection  39  acting as a mandrel.