CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 to Swiss Patent Application No. CH-01738/12 filed 26 Sep. 2012 and Swiss Patent Application No. CH-00395/13 filed 4 Feb. 2013, the entire contents of each are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a portioned package which under pressure in espresso machines is suitable for extraction and which contains a substance for preparing a drink, in particular of roasted and ground coffee, consisting of a truncated-cone-shaped capsule of plastic with a conical side wall, a head part integrally formed on the smaller diameter and having a sieve plate integrally formed as one piece for the piercing-free feed of an extraction fluid and of a circumferential flange on the wider end of the conical wall, said flange projecting from the conical side wall, wherein the flange has an annular head-part-side surface and an annular oppositely lying membrane-side surface, onto which a destructible membrane is welded, and moreover the head-part-side surface is provided with a circumferential seal. 
       BACKGROUND OF THE INVENTION 
       [0003]    The company Nestlé SA has been successfully selling portioned packages, with which coffee can be extracted under pressure in espresso machines, for more than 20 years. These portioned packages although being known in several shapes; it is however the conical capsules which have proven particularly successful on the market. The machines which are present for this comprise a so-called brewing chamber which largely corresponds to the shape of the capsules. The capsules are held in the machine in a clamped and sealed manner, whereupon several injection needles or tear-open tips penetrate into the capsule. The membrane is destroyed under pressure in a patterned manner at several locations according to the counter-pressure plate in the machine and the extraction fluid can thus practically exit through a sieve, on account of the water as an extraction fluid getting into the capsule under pressure and getting to the membrane of the capsule which is attached at the wider end. 
         [0004]    Various patents directed to these capsules have expired in the meantime, and capsules in competition have arrived on the market, and these are designed such that they can be used compatibly with already existing espresso machines. 
         [0005]    The compatible capsules which are present on the market today consist of plastic for ecological as well as economic reasons. This means that the capsules must be designed such that injection needles belonging to the machine do not come into contact with the portioned package of plastic, since the hot injection needles would cause a melting of the plastic capsules, which would lead to a bonding of the injection needles and thus would result in the exit openings of these needles becoming blocked. The tips heated by the hot water would soften the plastic and this plastic would form around the tip in a closing manner and handicap the correct entry of water. The plastic residues remaining on the tips moreover lead to a bluntening of the tips and these would no longer function correctly over time. Accordingly, these capsules are mostly not as tall as the original capsules of the company Nestlé SA and significantly more water gets into the brewing chamber of the machine and thus flows around the capsule on extraction. Only when the remaining space between the capsule and the brewing chamber is completely filled, does the water forcibly go into the plastic capsule. Only then can a sufficient pressure be built up, which leads to the desired destruction of the membrane 
         [0006]    This thus slightly modified manner of functioning leads to the fact that a greater sealing effect is necessary between the brewing chamber of the machine and the inserted plastic capsule. 
         [0007]    The existing circumferential flange is used for sealing, since the capsules and the brewing space neither correspond exactly to one another with regard to size nor to shape. With the known aluminium capsules of the company Nestlé SA, the flange comprises a crimpled edge. On closure of the brewing chamber, pressure is exerted on the flange and this deforms and adapts to the shape conditions. With the aluminium capsules, this is essentially effected by way of a plastic deformation of the silicone seal. A capsule is known on the market, with which a silicone seal has been attached in the corner region between the conical side wall and the outwardly directed flange which connects thereto. This however necessitates the use of a second material and its manufacture was accordingly complicated and expensive. 
         [0008]    For capsules which are compatible with the existing espresso machines and are manufactured of plastic, it was suggested to attach a labyrinth seal on the head-part-side surface of the flange by way of concentric rings integrally formed as one piece. This seal has a plastic deformability as well as an elastic deformability and thus may lead to an improved sealing. Such solutions are known for example from EP2284101 or WO2010/137954. 
         [0009]    The membrane-side surface of the flange until now was completely covered by the membrane itself, so that no seal was present between the membrane plate and the extraction plate of the brewing chamber. However, additional deformations occur when welding the membrane onto the flange and these significantly reduce the sealing on the membrane side. This problem was not recognised until now and one attempted to increase the closure force of the brewing chamber as an alleged solution. 
       SUMMARY OF THE INVENTION 
       [0010]    It is therefore an aspect of the present invention, to improve a portioned package, such that the sealing of a capsule of plastic is improved not only on the head part side but also on the membrane side. This aspect can be achieved by the invention in that a seal is attached on the circumferential flange also on the membrane side, and the destructible membrane preferably has a smaller diameter than the outer diameter of the flange. In this manner, the capsule according to the invention can be held in the brewing chamber of an espresso machine in an essentially tighter manner on all sides. 
         [0011]    Further advantageous designs of the subject matter of the invention are to be deduced from the following and their design and functioning is described in the subsequent description with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Embodiments of the subject matter of the invention are represented in the drawings. 
           [0013]    There are shown: 
           [0014]      FIG. 1  shows a portioned package of the shape of interest here, in a perspective representation essentially from the side and 
           [0015]      FIG. 2  the same portioned package, again in a perspective representation, more from the top with a view to the sieve plate. 
           [0016]      FIG. 3  shows a part section through the portioned package according to the invention, in the region of the side wall and the flange, with a first embodiment. 
           [0017]      FIG. 4  shows a part section through the portioned package according to the invention in the region of the side wall and flange, with a second embodiment. 
           [0018]      FIG. 5  shows a perspective representation of a part detail through the circumferential flange in the region of the seals with rectangular recesses. 
           [0019]      FIG. 6  shows a perspective representation of a part detail through the circumferential flange in the region of the seals with hexagonal recesses. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The portion packaging according to the invention is indicated in its entirety at  1  and is shown in a perspective position in the  FIGS. 1 and 2 . The portioned package  1  consists essentially of a truncated-cone-shaped capsule  1 ′. This truncated-cone-shaped capsule  1 ′ is formed by a conical side wall  2  and has a head part  3 . A sieve plate  4  is formed in the head part  3 . The sieve plate  4  in the head part  3  has a number of water entry openings  11 . The head part  3  is integrally formed as one piece with the side wall  2  at its end with the smaller diameter. An outwardly projecting, circumferential flange  5  is likewise integrally formed as one piece on that end of the conical side wall  2  with the greatest diameter. This circumferential flange  5  on the side which is away from the head part  3  (see  FIGS. 3 and 4  for this) comprises an annular surface which is indicated as a membrane-side surface  7 . A destructible membrane  6  is welded on the membrane-side surface  7 , as is likewise evident in the  FIGS. 3 and 4 . The individual regions of the cone-shaped capsule  1 ′ are hereinafter described in a detailed manner 
         [0021]    As has already been mentioned, the head part  3  is integrally formed on the end of the truncated-cone-shaped capsule  1 ′ of the head part  3 , said end being the smaller one in diameter. 
         [0022]    This head part  3  has a relatively flat, conical edge  12 . This conical edge is part of a truncated cone with an opening angle of 120° to approx. 160°. The truncated region of this cone forms a plane which forms the sieve plate  4 . The mentioned water entry openings  11  are recessed in the sieve plate  4 . The water entry openings  11  can in principle be arranged distributed over the surface in a roughly uniform manner In the preferred example represented here, these water entry openings  11  are however arranged distributed in a circular manner in the region of the perimeter of the sieve plate  4  at uniform distances. The arrangement shown here is selected for reasons of flow technology, in order with this, to avoid a mainly central through-flow of the heated water, but despite this to achieve a surfaced wetting of the ground product. The ground product consists of ground coffee beans. Moreover, it is clear and in particular evident in  FIG. 1 , that the sieve plate  4  in the head part  3  is arranged offset slightly in the direction of the circumferential flange  5  which is to say to the destructible membrane  6 . A cylindrical edge or a wall region  13  arises by way of this. This cylindrical wall region  13  effects an increased strength of the capsule  1 ′. 
         [0023]    Shortly below the head part  3 , at least one circumferential, conical support surface  14  is formed in the conical side wall  2 , in the region close to the head part. This conical support surface can sealingly cooperate with a rubber sleeve which is present with the espresso machine, into which the capsule  1 ′ is inserted for extraction. This conical support surface  14  however is not absolutely necessary and it only makes sense if the respective espresso machine envisages such a rubber sleeve seal. 
         [0024]    The special design of the circumferential flange  5  is described hereinafter and thereby it is particularly  FIGS. 3 and 4  which are referred to, which each show a vertical part section through the portioned package according to the invention, in the region of the side wall and the flange. One recognises the obliquely upwardly running conical side wall  2 , on which the circumferential flange  5  is integrally formed in a radially outwardly directed manner According to the invention, in each case a circumferential seal  8 ,  8 ′ is attached on this flange  5  on both sides, which is to say on the one hand on an annular head-part-side surface  9  and on the other hand on the annular membrane-side surface  7 . In principle, the circumferential seals  8 ,  8 ′ can be formed in an infinite manner. Preferably, the seals  8 ,  8 ′ however consist of a multitude of recesses  20  which are arranged next to one another, do not communicate with one another and are separated from one another by webs  21 , wherein the recesses  20  form retention spaces and the webs  21  form multiple sealing locations. This arrangement of recesses  20  and webs  21  forms an essentially honeycomb structure. The sealing function results on the one hand from the webs which run essentially linearly as well as closed in a small-spaced as well as large-spaced manner and which due to the plastic and elastic deformation of the plastic capsule form a multitude of micro-chamber regions which are closed in a separated manner several times in one another and behind one another and which at least greatly render the propagation of leakage flows difficult in all directions, and on the other hand of course also out of the recesses or micro-chambers themselves, which are capable of holding back or storing any occurring slight leakage flows. 
         [0025]    As has already been mentioned initially, the invention lies in seals  8 ,  8 ′ being attached on the head-part-side surface  9  of the flange  5  as well as on the membrane-side surface  7  of the flange  5 . These seals are usually designed as sealing lips which run around the capsule side wall  2  in concentric circles. With such concentric sealing lips, there is always the danger that the sealing lips are completely buckled due to the pressure, with which the edge of the brewing chamber presses onto the flange, and as a result even coming to lie in an overlapping manner and thus the sealedness is not longer achieved. For this reason, one envisages the region between the centring bead  10  and the side wall  2  on the head-part-side surface  9  comprising a multitude of recesses  20  which are arranged next to one another. The recesses  20  can thereby have different shapes. Thus the recesses as are shown in  FIGS. 5 and 6  by way of two examples can for example have a square or hexagonal outline and as a whole have a concavely bent or concavely truncated-pyramid-like structure. The present recesses in  FIGS. 3 and 4  are basically represented on the head part side as well as on the membrane side. Rectangular, rhomboid, trapezoidal or triangular layouts which are encompassed by the webs  21  are also considered, apart from the layouts represented here. 
         [0026]    In the examples according to  FIGS. 3 and 4 , the membrane-side seal  8 ′ is also designed of recesses  20  and intermediately lying webs  21 , similarly or equally to the head-part-side seal  8 . In the example of  FIG. 3 , the recesses  20  or the webs  21  cover the entire membrane-side surface  7  of the flange  5 . The membrane  6  here is thus welded directly onto the webs  21 . With the welding itself, the webs  21  are thereby softened and at least partly reduced in height. A practically complete sealedness is achieved with this. The structure of the circumferential seals  8 ,  8 ′ with recesses  20  and webs  21  is also advantageous in the case of ultrasound welding, since hereby the essentially linear-like courses of the webs simultaneously serve as energy conducting means, by which means an improved and quicker welding is effected. 
         [0027]    Moreover, in  FIG. 3  it is shown once again that the flange  5  will naturally comprise a thinned region  15  due to the seals  8 ,  8 ′ present on both sides. The thickness of the flange  5  as well as the thickness of the thinned region  15  can thereby be naturally selected such that as good as possible sealing characteristics arise. Thus it can be advantageous if the membrane  6  has a thickness which corresponds maximally to the thickness of the thinned region  15  of the flange  5 . 
         [0028]    Alternatively, an example is shown in  FIG. 4 , with which on the membrane-side, the flange  5  is only provided with a circumferential seal  8 ′ in the peripheral region, whereas a plane surface as the actual welding surface  16 , onto which the membrane  6  can be welded in the conventional manner, is present in the central region of the flange  5 . With this embodiment, the circumferential seal  8  and the circumferential seal  8 ′ can at least partly overlap in the projection in the radial direction. A bonded membrane can also be realised with such an embodiment. The tips of the webs  21  can thereby project beyond the outer surface of the membrane  6 , be as equally high as this outer surface, or the lower side of the membrane can also project slightly beyond the webs. If the capsule is used in a known machine, then on the one hand the edge of the brewing chamber presses onto the head-side surface  9  or onto the circumferential seal  8  which is present there, and additionally a certain pressure is exerted onto the centring bead  10 , so that the membrane-side seal  8 ′ is always pressed onto the counter-pressure plate of the espresso machine. Hereby, the webs  21  of both seals  8 ,  8 ′ are always also slightly deformed, which however is advantageous for the sealing. 
         [0029]    As has been described initially, many of the alternatively useable capsules are slightly less high that the brewing chamber, in which they are inserted and thus a part of the water always flows downwards along the side wall. The water would have to flow through the head-part-side seal  8  between the capsule and the brewing chamber edge bearing with pressure, so that this water not flowing through the capsule would be able to exit, and if the water were to get so far, then it would have to flow around the centring bead  10  and then additionally yet pressed at the lower side through the circumferential membrane-side seal  8 ′, before it could to the machine pour-out in the region of the membrane  6 . This would not happen in the normal case. If however for whatever reason, the capsule is not sufficiently subjected to through-flow or the flow paths through the capsule are insufficiently open, for example due to the fact that the water entry openings  11  are partly or completely closed due to the formation of a plastic film on manufacture, it is particularly the seal  8  which would be subjected to particularly high loading. The seals and in particular the seal  8  must therefore be dimensioned such that the desired sealedness is achieved in the normal case, and in the case of malfunctioning the safety of the espresso machine remains ensured. 
         [0030]    All references cited herein are expressly incorporated by reference in their entirety. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. There are many different features to the present invention and it is contemplated that these features may be used together or separately. Thus, the invention should not be limited to any particular combination of features or to a particular application of the invention. Further, it should be understood that variations and modifications within the spirit and scope of the invention might occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           1  portioned package 
           1 ′ capsule truncated-cone-shaped 
           2  conical side wall 
           3  head part 
           4  sieve plate 
           5  circumferential flange 
           6  destructible membrane as cover 
           7  annular, membrane-side surface of the flange 
           8  circumferential seal (on the head part side) 
           8 ′ circumferential seal (on the membrane side) 
           9  annular head-part-side surface of the flange 
           10  centring bead 
           11  water entry opening 
           12  relatively flat conical edge 
           13  cylindrical edge/wall region 
           14  conical support surface 
           15  thinned region of the edge 
           16  weld surface 
           20  recesses 
           21  webs
Truncated-cone-shaped capsules of plastic can have a lower construction height than the widespread aluminium capsules for creating an espresso, in order to avoid the hot water injection needles penetrating into the portioned package of plastic and bonding. By way of this, a greater quantity of heated water at an increased pressure prevails outside the truncated-cone-shaped capsule with its conical side wall and the circumferential flange projecting circumferentially therefrom. This necessitates greater demands on the sealing of the truncated-cone-shaped capsule with respect to the brewing chamber, in which the capsule is introduced. It is therefore suggested to attach a seal in each case on the flange on the head-part-side surface as well as the opposite membrane-side surface.