SELF-OPENING PLASTIC CLOSURE

Abstract

Self-opening plastic closures having a pouring spout including a flange, a cutting member that is moveable in the spout and a screw cap for actuating the cutting member. In this invention, the cutting member carries out a translatory cutting motion by the rotational movement of the screw cap. In order to open the sealed packaging, to which the plastic closure is attached, different torques are brought to bear. According to this invention, first means and second means engage with one another successively to produce different advance paths for each revolution of the screw cap.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a self-opening plastic closure including a pour-out spout with a flange for connection to a single-layer or multi-layer packaging foil of a closed packaging, with a cylindrical cutting element movably guided within the pour-out spout, and with a screw cap with a lateral wall having an inner thread and with a cover surface, wherein the screw cap is screw-connected to the pour-out spout with an outer thread, and the screw cap and the cutting element include elements which convert the screw movement of the screw cap into a purely translatory relative movement of the cutting element to the pour-out spout.

2. Discussion of Related Art

Self-opening plastic closures are to be understood as closures which are welded or bonded onto a completely closed receptacle of a single-layer or multi-layer packaging foil, and include a cutting element which when screwing open the screw cap for the first time, cuts open the packaging foil and holds it in the opened condition. The re-closure ability of the closure from then on is only effected by the screw cap.

Plastic closures of this type have been widespread on the market for practically 20 years. Two different types have already been disclosed in one of the earliest application of a closure of this type. In particular, such self-opening plastic closures are either provided with a rotating cutting element or with a cutting element which executes a purely translatory movement, such as known from European Patent Reference EP 0328652. The cutting element is guided axially in the pour-out spout, and on an upper edge includes a ramp-like advance device, which with a corresponding ramp-like end-face of an annular wall segment presses this cutting element downwards when screwing off the cap. Accordingly, the cutting element includes a multitude of perforating teeth which are distributed over the entire periphery, with the exception of a short section without teeth, in order to avoid the packaging foil being completely separated from the packaging and falling into the receptacle. One problem with such a solution is thus the force to be mustered. The complete force to be applied must practically be mustered with only a quarter revolution of the screw cap. These closures could not assert themselves on the market due to the high forces which are necessary in order to open such a closure.

An earlier version of a self-opening plastic closure with a rotating cutting element is known from PCT Publication WO 95/05996. With this closure, the pour-out spout includes an inner thread, in which the cutting element with an outer thread is mounted. The screw cap which has a peripheral lateral wall and a cover surface, on the inner side of the cover surface has at least one catch which on screwing open cooperates with a catch on the inner wall of the cutting element and then screws the cutting element downwards while the screw cap is screwed away upwards. Here too, the cutting element includes a multitude of perforating teeth which also all act simultaneously upon the packaging foil. Here too, a very large force is required, in order to carry out the opening, wherein here however one requires less force due to a significantly longer screw path. Despite this, it could initially be hardly realized for such a packaging foil to be opened, in particular if the so-called composite foils consist of a plurality of layers of plastic, cardboard, aluminium and once again plastic. Accordingly, it is envisioned to provide the packaging with a punched opening and bonding or welding this opening with a thin foil which can be easily cut open. Such solutions of course are expensive and complicated, and have the great disadvantage that the closures must be welded on in a very precise manner with regard to location, so that only the applied patches need to be severed and that the cutting element does not partially also need to sever the composite foil of the packaging.

Although one has then alternatively incorporated notches into such composite foils, wherein these notches only went down to the barrier layer, so that the cutting element only needed to sever this barrier layer and the plastic foil lying therebelow, however, clearly this solution once again demands a significantly greater precision of the assembly of the plastic closure onto the packaging.

A further variant is known from PCT Publication WO 2004/000667. Here, the advance of the cutting element in a first step is effected in a purely translatory manner by way of a drive, as is already known from the mentioned European Patent Reference EP0328652, and on reaching its deepest position, the cutting element from then on only rotates.

Whereas initially and particularly in the context of so-called cardboard composite packaging, one operated with a multitude of perforating teeth, later one has predominantly departed from this approach. One main reason for this multitude of perforating teeth is to be seen in the fact that the cardboard layer of such packaging requires a relatively high force, in order to be pierced. The multitude of teeth then indeed no longer effects a cutting, but more of a sawing.

The structure of such cardboard composite foils however has been changed over the years. One the one hand the cardboard layer has become increasingly thinner, and on the other hand several different layers of plastics have been applied, which in principle have again and again placed different demands upon the cutting element. Accordingly, a multitude of patent applications concern themselves with the shape and the arrangement of the perforating teeth and cutting teeth. Typical examples of such designs for example are to be deduced from PCT Publication WO 2004/083055 or European Patent Reference EP 1533240. An even more complex arrangement is shown for example in European Patent Reference EP 1795456. A reason for the many embodiments, as already mentioned, are the different types packaging foils, wherein in particular bag pouches (tubular bags) which have recently become widespread on the market and which are purely of plastic composite foils are a reason. Whereas the perforation is effected relatively reliably with only one or few perforating teeth in many cases, the subsequent cutting activity however is much more of a problem. These two different activities specifically, during the perforation, necessitate a relatively high force with a simultaneously low relative movement, whereas subsequently with the cutting procedure, a significantly reduced force with as large as possible a relative movement of the cutting edge relative to the foil to be severed is necessary. Here, no difference is made with the plastic closures which are obtainable on the market.

Also, it has been found that with self-opening plastic closures with a rotating cutting element, the foil to be cut, on account of its high elasticity as is practically the case of all polyethylene, leads to the material being drawn out and simultaneously accumulating on the cutting edge in the rotation direction and thus practically rendering the cutting edge ineffective. This then either leads to an incomplete line of cut or to an uncontrolled tearing of the packaging foil. This only partly opened container then only allows for a poor emptying.

It is thus one object of this invention to provide a self-opening plastic closure of the initially mentioned type, which can be actuated with a different force in dependence on the advance path, in order to master the problems which have been discussed.

SUMMARY OF THE INVENTION

The above object and others are achieved by a self-opening plastic closure as described in this specification and in the claims, wherein envisaged means include a first and a second advance mechanism which engage one after the other and which effect different axial advance paths per revolution.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous embodiments of the subject matter of this invention are discussed and deduced in view of the following description and the drawings, wherein:

FIG. 1 shows a perspective view of an assembled, self-opening plastic closure, in a view from above;

FIG. 2 shows a view onto a lower side of the plastic closure of FIG. 1;

FIG. 3 shows a screw cap of the self-opening plastic closure, in an axial vertical section;

FIG. 4 shows a perspective view onto the lower side;

FIG. 5 shows an axial vertical section taken through the pour-out spout;

FIG. 6 shows a perspective view of the pour-out spout of FIG. 5;

FIG. 7 shows the cutting element in a perspective view;

FIGS. 8 and 9 show cutting elements and the pour-out spout manufactured as one piece, together before applying the screw cap, in two different perspective views; and

FIGS. 10-13 show the assembled, self-opening plastic closure, in each case in a diametrical section, at different stages of opening.

DETAILED DESCRIPTION OF THE INVENTION

One possible design of the self-opening plastic closure according to the invention and which in its entirety is indicated at element reference numeral 1 is perspectively shown in FIG. 1. In this view, one can practically only recognize the screw cap 2 and that part of the pour-out spout 3 which is not covered by the screw cap. This non-covered part of the pour-out spout 3 is practically only the peripheral flange 31 at the end. From the outside, on the screw cap 2, one can recognize its peripheral lateral wall 20, on whose lower end a guarantee strip 22 is integrally formed via suitable predetermined breakage bridges which are not visible here. The peripheral lateral wall 20 carries the upper cover surface 21. A multitude of gripping ribs 29 which increase the gripping ability for the user on handling the screw cap are incorporated at the outside on the lateral wall 20.

The same, self-opening plastic closure 1 is represented obliquely from below in the assembled condition in FIG. 2. In the position shown here, the self-opening plastic closure 1 is represented in an intermediate position, with which the cutting element 4 with the perforating teeth arranged thereon is represented already projecting slightly out of the pour-out spout 2, and the cutting element 4 is therefore at least partly visible. The pour-out spout 3 from now on is partly visible from the lower side, so that one now recognizes an energy directing rib 32 on this lower side. The design of the energy directing rib is represented here as a single, peripheral rib, but other design forms or shapes of such energy directing ribs 32 are known, and their design is accordingly adapted to the weld connection which is to be formed, and to the material pairing.

The three parts which form the self-opening plastic closure are hereinafter described individually and their interaction explained afterwards. The screw cap 2 in the FIGS. 3 and 4 is represented on its own. As every screw cap, this includes the already mentioned lateral wall (skirt) 20 and the cover surface 21 terminating the screw cap. The likewise already mentioned guarantee strip 22 is integrally formed here via predetermined breakage bridges not specially shown here, below the lateral wall in an aligned manner. Here, one can recognize the inner thread 23 on the lateral wall 20, in particular in the sectioned view according to FIG. 3. This inner thread 23 serves for interacting with an outer thread on the pour-out spout 3. A first annular wall 24 can be recognized in this sectioned drawing and this in this sectioned drawing has a different height. The first annular wall 24 in this figure at the right side of the middle axis is higher than on the left of the middle axis. The first annular wall 24 in this embodiment is completely peripheral and runs from a lowest point to the highest point, wherein the lowest point represents the starting point on opening for the first time, and the highest point corresponds to an end point after a rotation of 360°, wherein this represents the end point of the advance path of a first advance mechanism.

The ramp-like first annular wall 24 has a sliding surface 25 which points away from the cover surface 21. This sliding surface 25 then cooperates with a second sliding surface of a first advance mechanism, wherein this will be dealt with later. A second annular wall 26 is integrally formed on the lower side of the cover surface 21, concentrically to the first annular wall 24, offset inwards. This second annular wall 26 has the same height over its entire periphery. The axial length of the second annular wall 26 here is larger than the axial length of the lateral wall 20. This is thus coherent so that the screw cap 2 in the assembled condition is held with its guarantee strip 22 via the flange 31 of the pour-out spout and distanced to this. An outer thread 27 is integrally formed on the outer side of this second annular wall 26. This outer thread 27 forms part of a second advance mechanism.

In principle, four concentric annular walls are integrally formed below the cover surface 21, wherein the outer annular wall represents the lateral wall 20 and the innermost annular wall forms the so-called second annular wall 26. Between the second annular wall 26 and the lateral wall 20, from the inside to the outside follows firstly the first annular wall 24 and thereafter an annular wall forming a so-called sealing olive 28 which in the closed condition of the closure after opening for the first time comes to bear on the inner side of the pour-out spout in a sealing manner. The packaging foil is still closed in the assembled condition before opening for the first time, and the sealing function of the sealing olive 28 is not yet necessary.

The pour-out spout 3 is shown on its own in each of the FIGS. 5 and 6, wherein FIG. 5 shows a diametrical section and FIG. 6 a perspective view, viewed from above into the pour-out spout. The pour-out spout 3 includes a cylindrical pour-out 30 of the one lower, edge-side peripheral flange 31. This flange 31 comprises the mentioned energy directing rib 32 on its lower side serving for being attached onto a packaging receptacle for this. Basically, the flange can be bonded on such a packaging, wherein this is particularly the case with so-called brik packaging, which include multi-layered packaging foils which comprise a cardboard layer, single-layer or multi-layer plastic and at least one barrier layer. The pour-out spout, and thus the complete, self-opening plastic closure can also be welded on such a packaging foil, in particular if the outermost layer of the packaging foil is a plastic layer. Thus, here it is mostly only a welding and hardly a bonding which is considered if the self-opening plastic closure 1 is attached onto a bag pouch which mostly consists of a complex, multi-layered plastic foil with a barrier layer. An axially running guide rib 34 can be recognized on the inner side of the cylindrical pour-out 30. This axial guide rib runs from approximately the upper edge of the cylindrical pour-out 30 to the lower edge of the pour-out 30. This axial guide rib 34 serves for the secure axial guiding of the cutting element 4 which is yet to be described, within the cylindrical pour-out 30 of the pour-out spout 3. Moreover, several detent lobes 35 are arranged on the inner wall of the cylindrical pour-out 30 in the lower region relative close to the plane which defines the peripheral flange 31. Actually, this is practically two detent lobes 35 which are arranged directly above one another. These serve for holding the cutting element in a defined lowermost position. Moreover, several separated predetermined breakage bridge parts 36 can be likewise recognized on the inner wall of the cylindrical pour-out 30 in the upper quarter which is discussed in more detail later. The abutment ribs 37 which are attached on the outer side of the cylindrical pour-out 30 and which extend down to the peripheral flange 32 serve for interacting with the guarantee strip. Finally, in FIG. 6 one yet recognizes a notch which is recessed on the outer periphery of the flange 31 and which forms an orientation notch 38 which merely serves for the orientation of the different parts in an assembly plant.

The cutting element is shown on its own in a perspective view in FIG. 7 and it comprises a cylinder wall 40 whose upper edge is designed as a ramp-like face wall 41. This ramp-like face wall with regard to length and gradient is designed the same as the ramp-like annular wall 24 of the screw cap 2. The ramp-like face wall 41 comprises a sliding surface 42 which in the assembled condition of the self-opening plastic closures 1 lies on the sliding surface 25 of the first ramp-like annular wall 24. Here, several perforating teeth 43 are integrally formed on this edge in the axial direction of the sliding surface 42. Each perforating tooth 43 is delimited by perforating edges 44 and together they enclose an acute angle. Cutting edges 45 are subsequent to these perforation edges 44, at both sides. Two cutting edges 45 which are directed to the same perforating tooth 43 in each case together enclose an obtuse angle. The perforating teeth 43 with the acute angle which the perforating edges 44 enclose, only execute a small cutting function, but practically carry out only a piecing function, in the case of an axial movement. The subsequent cutting edges 45 which run in a relatively shallow manner, with the continued, purely translatory advance of the cutting element which is effected in the axial direction and in the direction of the packaging foil now execute a significantly greater relative movement, with regard to the peripheral line per advance path section. The cutting movement is thus effected immediately after the perforation of the packaging foil with the second advance mechanism. Trials have shown that from now on, the cutting movement immediately continues the incisions which arise on perforation and are in the running direction of the perforating edges, into a cutting line.

Reinforcement ribs 491 which extend from a peripheral collar 47 to as closely as possible to the tip of the respective perforating tooth 43 are integrally formed on the outer side of the cylinder wall 40 of the cutting element 4. The peripheral collar 47 runs in a plane perpendicular to the middle axis of the cutting element. The upper edge of the peripheral collar 47 is arranged at the height of the lowermost point of the ramp-like face wall or sliding surface 42. The peripheral collar 47 comprises a guide recess 49, at least at those locations, at which the axial guide rib 34 is arranged in the pour-out spout. Also, several separated predetermined breakage bridges 48 which before the assembly connect the cutting element 4 to the pour-out spout 3, are to be recognized on the outer side of the peripheral collar 47. These separated predetermined breakage bridges 48 are connected to the separated predetermined breakage bridges 36 before assembly.

The cutting element 4 and the pour-out spout 3 together form a single-piece construction unit 70 which in the FIGS. 8 and 9 is shown in a perspective view with different viewing angles in each case.

The mentioned orientation notch 38 in the flange 31 of the pour-out part 3 is finally of significance, since the pour-out part 3 and the cutting element 4 are preferably manufactured as a single-part unit 70. The effort on production and assembly is thus reduced. The single-part unit 70 is realized such that the cutting element 4 lies completely within the pour-out 30 of the pour-out spout 3. In this position, the highest point of the ramp-like face wall 41 of the cutting element 4 at least approximately lies in the plane which is spanned by the upper edge 39 of the cylindrical pour-out 30.

Now, on assembly, the screw cap 2 is placed onto the single-part unit 70, wherein the screw cap is aligned so that the highest point 493 of the ramp-like face wall 41 comes to bear on that point which corresponds to the point which lies closest to the cover surface 21 on the first ramp-like annular wall 24 of the screw cap 2. On axially pushing together, preferably the predetermined breakage bridges between the peripheral collar 47 and the inner wall of the pour-out 30 are separated preferably at the last moment of the pushing-together, so that only the separated predetermined breakage bridges 36 and 48 continue to be present.

The cutting element 4 is simultaneously moved slightly axially downwards, so that the point of the cutting element 4 which is lowermost in the axial direction, specifically the tips of the perforating teeth 43 is still above the plane which defines the lower side of the flange 31. It is thus ensured that the plastic closure 1 does not lie on the packaging foil of the receptacle, on which it is to be fastened, already when welding on the assembled, self-opening plastic closure 1. This position is now represented in FIG. 10 in a diametrical section. This position shows the self-opening plastic closure 1 according to this invention, in the assembled position before opening for the first time. The predetermined breakage locations between the screw cap 2 and the guarantee strip 22 which is integrally formed thereon are still intact, but since the diametrical section does not run through a predetermined breakage bridge, this cannot be recognized in the figure. The first advance mechanism 50 is in its starting position in this position. This first advance mechanism 50, as mentioned, includes the first ramp-like annular wall 24 with its sliding surface 25, wherein its sliding surface 25 lies on the sliding surface 42 of the annular face wall 41 of the cutting element 40 over the entire periphery.

The screw cap 2 is now represented rotated by 360° in FIG. 11. On the left side one now recognizes the ramp-like face wall 41 which is practically at the highest point, whereas the highest location of the ramp-like annular wall 24 has just been exceeded and therefore is now only represented in a dotted manner. The opposite position on the right side shows the ramp-like annular wall 24 which here is only half as high, since the sliding surface 42 on this side has already moved by just as much downwards.

The second advance mechanism 60 now assumes its function in this position, in which the first advance mechanism has now reached its maximum advance path. As is evident on the right as well as left of the middle axis, this second advance mechanism 60, including the outer thread 27 on the second annular wall 26 is meshed with the inner thread 492 on the cylinder wall 40 of the cutting element 4. In this position, the first advance mechanism 50 as described in FIG. 10 has now moved the cutting element 4 already so far downwards in the direction of the flange, that the perforating teeth 43 lie below the plane which is spanned by the flange. The perforating teeth 43 have already perforated the closure foil in the case that the self-opening plastic closure is welded on a packaging foil.

If the screw cap 2 is moved by a further complete revolution, then the cutting element 4 is once again moved further in the direction of the flange 31 and not only the perforating tooth with its perforating edges 44, but also the adjacent cutting edges 45 just as the fold-over edge 46 now lie below the plane spanned by the peripheral flange, and the packaging on which the self-opening plastic closure 1 is attached, is now completely cut open and only continues to be connected to the packaging in the region of or near the fold-over edge 46. The cut-open packaging foil is folded over to outside the region of the pour-out 30. In the shown position, the inner thread 23 is connected to the outer thread 33 of the pour-out spout, as also the outer thread 27 on the second annular wall 26 is still meshed with the inner thread 492 of the cutting element 4.

If one now screws the screw cap 2 again by half a revolution, then the position shown in FIG. 13 is reached. The inner thread 492 is no longer meshed with the outer thread 27 on the second annular wall 26. However, on the left side in this figure, one simultaneously recognizes that the peripheral collar 47 on the cutting element 4 is snapped in with the detent lobes 35 on the inner side of the pour-out 30. With this, the cutting element 4 now remains in this position, even if the screw cap 2 is still completely screwed off from the pour-out spout 3. After one has removed a share of the contents out of the packaging and screwed the screw cap 2 back on, then with each opening and closing procedure, it is now only the screw cap 2 which moves, while the cutting element 4 remains in the unchanged position.

As previously mentioned, only a preferred embodiment is shown in the drawing. Further embodiments which are not described here are also possible without departing from the inventive concept. Thus of course all 3 components of the self-opening plastic closure 1, specifically the screw cap 2, the pour-out spout 3 and the cutting element 4 can all be manufactured separately. Here too, the described sequence of the first and second advance mechanism 50, 60 can of course be changed. In other words, the first annular wall can be designed as a normal cylindrical annular wall and be provided with suitable threads, whereas the second annular wall is then designed as a ramp-like annular wall. This second annular wall would then need to interact with the ramp-like face wall of the cutting element. Although this solution is of course also conceivable, the representation of this solution however has been omitted, and this variant is less preferred compared to the represented embodiment, because such a variant reduces the diameter of the cutting element and accordingly, in order to obtain the same opening, the whole self-opening plastic closure would need to be designed larger, which here would entail an increased material consumption.

Apart from the explicitly described solution and the variants mentioned above, it is possible to realize the first as well as the second advance mechanism both with a thread or both with advance ramps. These with regard to height merely need to be arranged so that both advance mechanisms cannot be engaged simultaneously.

Also, the first advance mechanism 50, instead of extending over 360° as shown, can be also designed from two ramp-like sections extending over 180° . This leads to a symmetrical force transmission, wherein the ratio of the advance path per revolution increases, just as the necessary force effort on opening for the first time.

Instead of the variant with three perforating teeth which is shown here, also only one or two perforating teeth or more than three perforating teeth can be present. This is made dependent on the diameter of the self-opening plastic closure 1. If one provides only one perforating tooth 43, then the adjacent cutting edges 45 extend in a gapless manner about at least two thirds of the periphery. The fold-over edge 46 then lies diametrically opposite the perforating tooth 43.

Claims

1. A self-opening plastic closure (1) including a pour-out spout (3) with a flange (31) for connection to a single-layer or a multi-layer packaging foil of a closed packaging, with a cylindrical cutting element (4) movably guided within the pour-out spout (3), and with a screw cap (2) with a lateral wall (20) with an inner thread (23) and with a cover surface (21), the screw cap (2) screw-connected to the pour-out spout (3) with an outer thread (33), and the screw cap (2) and the cutting element (4) converting a screw movement of the screw cap (2) into a purely translatory relative movement of the cutting element (4) to the pour-out spout (3), the converting comprising a first advance mechanism (50) and a second advance mechanism (60) engaging one after the other and effecting different axial advance paths per revolution.

2. A self-opening plastic closure according to claim 1, wherein the first advance mechanism (50) includes a first ramp-like annular wall (24) integrally formed on an inner side of the cover surface (21) of the screw cap (2), and a mutually opposite face wall (41) running in a ramp-like manner on the cylindrical cutting element (4).

3. A self-opening plastic closure according to claim 1, wherein the second advance mechanism (60) includes an inner thread (492) on the cylindrical cutting element (4) and of an outer thread (27) on a second angular wall (26) arranged on an inner side of the cover surface (21) in the screw cap (2).

4. A self-opening plastic closure according to claim 3, wherein the second annular wall (26) is arranged concentrically within the first annular wall (24).

5. A self-opening plastic closure according to claim 1, wherein a gradient of the first advance mechanism (50) is less than a gradient of the second advance mechanism (60).

6. A self-opening plastic closure according to claim 2, wherein the cutting element (4) on an end which lies opposite the ramp-like face wall (41) has at least one perforating tooth (43) to which a cutting edge (45) connects in a peripheral direction at both sides, and a fold-over edge (46) is present outside a region of the cutting edges and of the at least one perforating tooth (43).

7. A self-opening plastic closure according to claim 6, wherein only one perforating tooth (43) with connecting cutting edges (45) is present, and the cutting edges (45) extend in a gapless manner about at least two thirds of a periphery and the fold-over edge (46) is arranged diametrically opposite the perforating tooth (43).

8. A self-opening plastic closure according to claim 6, wherein at least two perforating teeth (43) present and the cutting edges extend in a gapless manner on at least two thirds of the periphery, and the fold-over edge (46) is arranged in a remaining cutting-edge free region.

9. A self-opening plastic closure according to claim 6, wherein the cutting edges (46), which are adjacent the same perforating tooth (43) enclose an obtuse angle.

10. A self-opening plastic closure according to claim 6, wherein an axial advance path of the first advance mechanism (50) is capable of advancing the cutting element (4) so far until a transition of the at least one cutting tooth (43) to the adjacent cutting edges (46) at least approximately lies in a plane of the flange (31) of the pour-out spout (3).

11. A self-opening plastic closure according to claim 10, wherein the advance path of the second advance mechanism (60) is capable of advancing the cutting element (4) so far until the fold-over edge (46) at least approximately lies in the plane of the flange (31) of the pour-out spout (3).

12. A self-opening plastic closure according to claim 1, wherein the purely translatoiy movement of the cutting element (4) relative to the pour-out spout (3) is realized by at least one axially running guide rib (34) on the inner side of a cylindrical pour-out (30) of the pour-out spout (3), and a guide recess (49) is realized in a peripheral collar (47) which is arranged at the outside on the cutting element (4).

13. A self-opening plastic closure according to claim 12, wherein detent lobes (35) are present on the inner surface of the pour-out (30) at a height close to the flange (31), into which lobes in a lowermost advance position of the cutting element (4) its peripheral collar snaps in wherein the position is equal to the end of the advance path of the second advance mechanism (60).

14. A self-opening plastic closure according to claim 1, wherein the pour-out spout (3) and the cutting element (4) are manufactured in a separable manner as a single piece, as one component (70).

15. A self-opening plastic closure according to claim 2, wherein the second annular wall (26) is arranged concentrically within the first annular wall (24).