EP2125542B1 - Plastic closing device comprising a cutting collar - Google Patents

Abstract

The invention relates to a plastic closing device comprising a pouring part (1) for fixing onto packaging, a screw cap (2) that can be screwed onto the pouring part (1) and a self-opening collar (3) in the pouring part (1) that can be moved downwards with a screw action onto the packaging in order to open the latter. The screw cap (2) has a follower (24), which acts on a stop element (36) of the self-opening collar (3) and which, when the screw cap (2) is first opened, moves the self-opening collar (3) inside the pouring part (1) into a lower position onto the packaging in order to open the latter. When the pouring part (1) is subsequently closed by the screw cap (2), the self-opening collar (3) remains in the lower position. The self-opening collar has several cutting and/or piercing elements (32a, 32b) with a substantially quadrangular basic form. Said form is interrupted by a lower longitudinal edge comprising a sloping and a longer and flatter rising region. Said form makes the closing device suitable for various types of packaging.

Description

Technical area

The invention relates to a sealing device made of plastic with a cutting sleeve according to the preamble of claim 1. The closing device is particularly suitable for sealed packages, which contain a flowable content, preferably a drink.

State of the art

A generic closure device is off EP 1 088 764 known. This closing device consists of three parts, namely a screw cap, a lower part and a cutting sleeve. The lower part is tubular and has on its underside a peripheral flange with which it can be fastened on a beverage pack. The tubular part forms a spout, which can be closed by means of the screw cap. The cutting sleeve is also tubular and has at its lower end a cutting tooth. In the unopened state of the pack, the cutting sleeve is located inside the lower part and the screw cap is screwed onto the lower part If the screw cap is now rotated to open the closing device, thanks to a driver system, the cutting sleeve also rotates axially downward emotional. As a result, the package and in particular the film of the package is cut in a circular manner along a predetermined breaking point. After a predetermined angle of rotation, ie when the package is opened wide enough, the driver engagement between screw cap and cutting sleeve is released. In the following, the screw cap can be completely removed from the spout and, if necessary, placed on it again in a sealed manner, without the cutting sleeve projecting into the package being moved again. The cutting sleeve and the base are molded in one piece in a pre-assembly configuration in which they are secured coaxially to one another by radial connecting bridges. These bridges extend between the upper edge of the cutting sleeve and the underside of the base. These bridges are broken when the cutting sleeve is first pushed into the base.

The shape and design of such closures are theoretically no limits. In practice, however, they must be produced by injection molding. Furthermore, they should be made as cheaply as possible.

There are various types of packaging known that can be opened with such self-opener closures. Among the known packages are, in particular, composite packages comprising a layer of paper or paperboard laminated with one or more thin layers of plastic and / or metal. A typical composite package includes e.g. a cardboard layer, which is provided to the inside of the package with a thin layer of aluminum, which in turn is provided with a layer of polyethylene (PE). Lately, increasingly put through by packaging that have no cardboard layer more, but are formed from a relatively thick plastic film, in particular pure PE packaging, which are provided with one or more very thin barrier layer.

In the manufacture of the package, the package is usually weakened, eg pre-punched, in the area where the closure is later placed, to allow the cutting sleeve to more easily penetrate the package wall. There are various possibilities for this, depending on the structure of the packaging and on the manufacturing process. In a pure PE packaging, for example, a circular weakening line may be formed in the wall with a smaller wall thickness. In the case of composite packaging, a weakened area is generally formed by penetrating the cardboard layer as completely as possible in a circular area (for example, by pre-punching it). If this pre-punching is done before the carton is coated with the other layers, it will normally be the one from the carton cut out circular disc before coating with the other layers removed. Thus, a package is produced which has a circular area in the region of the later opening, which consists only of the thin film layers of aluminum and / or plastic, but in which no cardboard is present. In contrast, if the paperboard layer is perforated only after coating, the cut-out circular disc remains bonded to the foil layers.

For each of these differently structured packages usually another type of self-opening sleeve is used. So it is e.g. in a composite package having a circular area in the area of the opening which consists only of film layers, disadvantageous when the self-opening sleeve exerts a high axial force on the film layers ("pressing"). In this case, the film layers tend to evade this force by bulging toward the interior of the package. Instead, such a package should be separated as possible by cutting. Conversely, it is advantageous in packaging in which the cardboard disc is still present, especially when a compressive force is exerted.

Known self-opening closures also require a very accurate positioning of the closure on the intended and prepared by a weakening Publ opening area. If the positioning is not exactly centered in such closures, a clean opening of the packaging is often not guaranteed.

Out WO 03/002419 For example, a closure with a self-opening sleeve is known, which has two cutting elements, which are arranged to follow each other and have a triangular basic shape.

Also the WO 2006/089440 shows a self-opening sleeve with two triangular cutting teeth.

In the WO 2004/083055 triangular cutting teeth are also disclosed. In addition, there is a perforating tooth here. If a sheet of the laminated packaging material has not been cut cleanly by the cutting teeth, it will become punctured by the perforating tooth pierced.

The WO 2007/030965 discloses a self-opening sleeve having three teeth. Each of these teeth has a triangular basic shape, followed by a stiffening shoulder connects. When two teeth this shoulder in the direction of rotation of the tooth below, on the third tooth this leading formed.

Each of these self-opening sleeves is optimized for a particular type of packaging. Therefore, none of the self-opening closures will provide a satisfactory result in all the above-mentioned types of packaging, but will fail in at least one type of packaging.

Presentation of the invention

It is therefore an object of the invention to provide a closure device of the type mentioned, which can be produced inexpensively. It is a further object of the invention to provide a closure device which is capable of efficiently penetrating various types of differently constructed or differently prepared packages. It is a further object of the invention to provide a closure device which satisfactorily opens different types of packages even when not perfectly centered on a weakened area of the package.

These objects are achieved by a closing device having the features of patent claim 1.

The plastic closure device according to the invention has a spout part for attachment to a pack, a screw cap which can be screwed onto the spout part, and a self-opening sleeve which can be moved downwards in a screw-shaped manner in the spout part for opening the pack. The screw cap has at least one drive element or driver, which acts on at least one stop element of the self-opening sleeve and which causes the first time opening the screw cap moves the self-opening sleeve within the spout into a lower position toward the package to open it. During the subsequent closure of the spout part with the screw cap, the self-priming sleeve remains in its lower position. The Selbstöfnerhülse has at least two downwardly projecting cutting and / or Durchstosselemente, which are arranged on the circumference of the Selbstöffnerhülse and form a lower edge thereof. These cutting and / or piercing elements have a substantially rectangular shape. A relatively long, downwardly projecting longitudinal edge in the direction of rotation interrupts the rectangular shape and forms a downwardly projecting triangle, so that a projecting tip is formed. The longitudinal edge has with respect to the direction of rotation of the sleeve in front a downwardly sloping and then a rising region again, wherein the rising portion is longer and flatter than the sloping region and inclined with respect to a plane perpendicular to the longitudinal axis at a shallow angle.

This shaping of the cutting and / or piercing elements is the result of an optimization with regard to fundamentally contradictory requirements. It has been found that the proposed shape achieves a particularly secure and clean opening of the packaging, and equally reliable for different types of packaging (in particular laminated cardboard packaging with different types of weakening and PE film packaging). In this case, the leading rising portion of the longitudinal edge acts substantially during the rotation of the sleeve cutting, while the entire longitudinal edge, including the rear area, additionally acts oppressively in the downward movement.

The rising and / or falling area may be straight or curved. The rising area is preferably considerably longer than the sloping area and preferably has a length which is at least 2.5 times the length of the sloping area. The sloping region preferably encloses an angle of at least 40 °, particularly preferably approximately 50 ° to the horizontal (ie to a plane perpendicular to the axis of rotation), while the angle of the rising region to the horizontal is preferably less than 30 ° everywhere, particularly preferably less than 20 °. Between the rising area and the sloping area of the longitudinal edge is preferred at the location an obtuse angle, ie an angle of more than 90 degrees, formed.

Preferably, the downwardly extending longitudinal edge forms a cutting edge at least in its sloping region, i. The self-opening sleeve is formed in this area to the longitudinal edge towards a blade-like tapered. This facilitates the severing of the packaging. Preferably, a cutting edge is formed in the rising region. Thereby, e.g. Film material, which elastically spans across the longitudinal edge, is also severed efficiently in this area.

The cutting edge is preferably formed on an inner peripheral surface of the self-opening sleeve. In other words, the self-opening sleeve preferably tapers toward the longitudinal edge only on its outer circumference so as to form the cutting edge, while the inner circumference in the region of the longitudinal edge is constant. As a result, the cut material is displaced outwards, which contributes to a clean cut of the cut-out material disc of the package

Preferably, all cutting and / or piercing elements protrude equally far down. In this way they contact the weakening area of the packaging at the same time and perforate it in several places at the same time. Even if the perforation should not succeed at one point, such a safe opening is guaranteed. In addition, in this way a relatively large, uniform pressure exerted on the weakened area, which is particularly advantageous for certain types of packaging.

In order to achieve a force distribution that is as uniform as possible, the cutting and / or piercing elements (32a-32e) are preferably distributed equidistantly around the circumference

In addition, the self-opening sleeve may have at least one hold-down element which forms the lower edge with the cutting and / or piercing elements and serves to push the separated-out material disc of the packaging downwards in order to prevent it from hindering the pouring out. The hold-down element is then arranged in the direction of rotation of the cutting and / or piercing elements trailing.

In this case, preferably, the cutting and / or piercing elements are initially distributed successively and gleichabständig distributed on the circumference, and the distance from the hold-down element to the first cutting and / or piercing element in the direction of rotation is preferably greater than the distance of the cutting and / or piercing elements among themselves.

If a hold-down element is present, the self-opening sleeve preferably has three to five, in particular four cutting and / or piercing elements. Without hold-down element, it is advantageous if the self-opening sleeve has four to six, in particular five cutting and / or piercing elements. With a smaller number, the force distribution is less uniform, and the material thickness of each individual cutting and / or piercing element must be significantly increased, which makes the production more expensive. In turn, a larger number of such elements cause each individual element to become smaller, which is also unfavorable in terms of stability. If the number of elements is too large, the compressive force exerted by each element becomes too small, and clean cutting action can no longer be achieved. The optimum number is ultimately the result of a lengthy optimization in view of the different and sometimes contradictory requirements that must be met by the self-opening sleeve to make them suitable for various types of packaging.

For guidance, the self-opening sleeve preferably has an external thread, which meshes with an internal thread of the spout part, so that the self-opening sleeve rotates during its downward movement. The pitch of the external thread is preferably chosen so that the self-opening sleeve when unscrewing the screw cap rotates less than 360 degrees, in particular 300 degrees, performs.

Preferably, only a single drive element is present on the screw cap. Preferably, only a single stop element is correspondingly present on the self-opening sleeve. Preferably, this stop element is located in the area a front in the direction of rotation of the sleeve cutting and / or piercing element. However, it can also be provided more distributed over the circumference arranged stop elements, the driver engages only in one of them.

In the case of a single drive element or driver, the closure device is very simple. This minimizes the manufacturing costs. In particular, the closure material can be saved, since the driver system is reduced to an absolute minimum. Thanks to the simple form of the closing device also their production is simplified and the committee on non-quality-compliant closures is relatively low.

The driver preferably has a driving edge, which extends in the axial direction. The Mitnehmerkante then preferably has an inclined to the radial direction of the stop surface. In particular, the driver may be formed tooth-shaped, with the vertical driving edge and a back with an angle of inclination of a maximum of 45 °. The driver preferably has a height which corresponds approximately to the height of the spout part. The stop element may be an inner wall of the self-opening sleeve projecting nose, which has an edge extending in the axial direction and which extends only over part of the height of the self-opening sleeve. The nose may then have a rearward grip relative to the radial direction.

Further advantageous embodiments will become apparent from the dependent claims.

Brief description of the drawings

Figur 1

einen Längsschnitt durch eine Verschliessvorrichtung gemäss einer ers- ten Ausführungsform in einem Zustand vor ihrer ersten Verwendung;

Figur 2

die Vorrichtung gemäss Figur 1 bei abgeschraubter Schraubkappe;

Figur 3

eine Seitenansicht der Vorrichtung gemäss Figur 2;

Figur 4

eine Ansicht des Verschlusses gemäss Figur 2 von unten, montiert auf einer Packung;

Figur 5

einen Längsschnitt durch Ausgussteil und Selbstöffnerhülse der Vorrich- tung gemäss Figur 1 nach ihrer Herstellung;

Figur 6

eine perspektivische Darstellung der Vorrichtung gemäss Figur 1 von unten;

Figur 7

eine perspektivische Darstellung der Vorrichtung gemäss Figur 1 von der Seite;

Figur 8

eine Ansicht der Vorrichtung gemäss Figur 1 von unten;

Figur 9

eine Seitenansicht des Ausgussteils und der Selbstöffnerhülse gemäss Figur 1;

Figur 10

einen Schnitt durch A-A gemäss Figur 9;

Figur 11

einen Längsschnitt durch einen erfindungsgemässen Verschluss gemäss einer zweiten Ausführungsform;

Figur 12

eine perspektivische Darstellung des Verschluss gemäss Figur 11 und

Figur 13

eine Ansicht des Verschlusses gemäss Figur 11 von unten, montiert auf einer Packung.

In the following, the subject invention will be explained with reference to preferred embodiments, which are illustrated in the accompanying drawings. Show it:

FIG. 1

a longitudinal section through a closure device according to a first embodiment in a state before its first use;

FIG. 2

the device according to FIG. 1 with unscrewed screw cap;

FIG. 3

a side view of the device according to FIG. 2 ;

FIG. 4

a view of the closure according to FIG. 2 from below, mounted on a box;

FIG. 5

a longitudinal section through the pouring part and Selbstöffnerhülse the Vorrich- tion according to FIG. 1 after their production;

FIG. 6

a perspective view of the device according to FIG. 1 from underneath;

FIG. 7

a perspective view of the device according to FIG. 1 of the page;

FIG. 8

a view of the device according to FIG. 1 from underneath;

FIG. 9

a side view of the spout and the self-opening sleeve according FIG. 1 ;

FIG. 10

a section through AA according to FIG. 9 ;

FIG. 11

a longitudinal section through a closure according to the invention according to a second embodiment;

FIG. 12

a perspective view of the closure according to FIG. 11 and

FIG. 13

a view of the closure according to FIG. 11 from below, mounted on a box.

Ways to carry out the invention

In the FIGS. 1 to 10 an embodiment of a closing device or the self-opener closure is shown. Such closures are applied to packages with flowable content, in particular on beverage cartons with inside film. The pack preferably already has a predefined, but still airtight, spout opening in this area. Preferably, the cardboard is already perforated or otherwise weakened, but the underlying film is still intact.

The device is made of plastic by injection molding, wherein the individual parts can be made of the same or different plastic.

The device has, as in FIG. 1 can be seen, essentially a spout part 1, a screw cap 2 and a self-opening sleeve 3. Preferably, a guarantee strip 4 is additionally present, which is preferably produced in one piece with the screw cap 2. Spout 1 and self-opening sleeve 3 are preferably also made in one piece together. However, it is also possible to manufacture these separately.

The spout part 1 consists essentially of a sleeve-shaped spout 10 with a continuous spout opening and a spout 10 projecting outwardly flange 13, which is integrally formed on a lower end of the spout 10. This flange 13 is welded or otherwise secured to the package so that the spout 10 comes to rest over the predefined spout opening of the package.

The spout 10 has an external thread 12 and an internal thread 14. In the lower region of the spout 10, above the flange 13, webs 15 are arranged with protruding, undercut retaining lugs 15 ', as described below.

The screw cap 2 preferably has a cylindrical casing wall 21 and an approximately flat top surface 20. The cap 2 can be screwed by means of an internal thread 22 on the external thread 12 of the spout part 1. The jacket wall 21 is connected via predetermined breaking points 23 with the guarantee strip 4.

In the inner upper region of the cap 2, preferably a circumferential sealing lip 26 protrudes downward, which in the closed state of the cap 2 rests resiliently against the inside of the pouring spout 10.

The cap 2 has a single inwardly or downwardly projecting driver 24, which is preferably integrally formed on the inside of the top surface 20. The driver 24 preferably has a triangular basic shape, wherein it is formed bent along a concentric to the internal thread 14 circle. A driver edge 14 extends in the axial direction, wherein it preferably has an abutment surface which is inclined to the radial direction, ie forms a rear grip. A back adjoins in the opening direction of rotation of the cap 2 to the driving edge, wherein the back has an angle of inclination of a maximum of 45 °. The height of the driver 24 corresponds approximately to the height of the spout part 1, in particular of the spout 10.

The self-opening sleeve 3 is hollow-cylindrical and has a through opening. It consists essentially of a ring 30 with an external thread 31 and the ring 30 downwardly approximately vertically projecting cutting and / or piercing elements 32a - 32e. These cutting and / or piercing elements 32a-32e are distributed on the circumference of the self-opening sleeve 3 and arranged at a distance 33 from each other and form a lower edge thereof. Furthermore, at least one hold-down element 35 may be present at this edge. These elements will be described in more detail below.

The sleeve 3 has at least one, preferably exactly one stop element 36, as shown in FIG FIG. 2 is recognizable. The stop element 36 is an inner wall of the self-opening sleeve 3 protruding nose, which has an edge extending in the axial direction and which preferably only over a portion of the height of the self-opening sleeve 3 extends. Preferably, the nose has a stop surface inclined with respect to the radial direction. The nose preferably extends in the region of the external thread 31, wherein the external thread 31 expands over a greater height than the nose. The stop element 36 is preferably arranged in the direction of rotation of the sleeve 3 in the region of the first cutting and / or piercing element 32a, wherein it may be arranged in the front or in the rear region thereof or in between.

In FIG. 1 the cap 2 is screwed onto the spout part 1 and the self-opening sleeve 3 is located in the spout 10, wherein it does not project beyond this or the flange 13 downwards. The guarantee band 4 is intact. This is the situation as it is before the first use of the closure, in this position, the closure can be mounted on the package.

Now, if the cap 2 unscrewed, so the driver 24 abuts on the stop element 36. This is in FIG. 6 recognizable. If their surfaces are inclined, at least in part a positive connection takes place, which reinforces the connection between cap 2 and sleeve 3.

The external thread 31 of the sleeve 3 meshes with the internal thread 14 of the pouring part 1, so that the sleeve 3 rotates screw-shaped downward during the first unscrewing of the cap 2 within the pouring spout 10. If the cap 2 is removed, the engagement between driver 24 and stop member 36 dissolves.

In FIG. 2 the cap 2 is removed, the predetermined breaking points 23 broken to the guarantee strip 4 and the sleeve 3 has moved down so that it is now held only with its upper part in the lower region of the spout 10, with their teeth 32 a - 32 e, however Flange 13 projects downwards. This is the situation as it occurs after the shutter is first opened.

In FIG. 4 the position of use is again clarified, it can be seen that a portion D, which predefines the spout opening of the package K, not complete is separated, but remains attached to it over a small circle. However, it is held by at least one of the cutting and / or piercing elements 32e in an unfolded position.

The sleeve 3 now remains in this lower position, even if the cap 2 is replaced and tightened.

Like now in FIG. 3 can be seen, this embodiment has a total of five cutting and / or piercing elements 32a-32e. These are preferably of the same height. These elements are distributed gleichabständig distributed over the circumference of the sleeve 3.

They are preferably identically shaped and the same size. They have a substantially rectangular shape, wherein in each case a downwardly projecting longitudinal edge interrupts the rectangular shape. It is inclined, with the height of the element in the direction of rotation of the sleeve 3 decreases toward the rear. The longitudinal edge is relatively long, so that it is greater than the distances 33 between the elements. Preferably, it is at least twice as long as the distance 33 between them.

In this example, the longitudinal edge is formed relatively blunt, so that the elements act more or exclusively as a pusher or piercer and not as cutting elements.

You can, however, like this in the FIGS. 11 to 13 is shown to be formed as cutting elements without their basic shape has to be changed significantly. In the further preferred embodiment shown here is instead of the straight longitudinal edge according to FIG. 3 formed a longitudinal edge, which first falls down in the direction of rotation of the sleeve 3 and then rises, so that a downwardly projecting tip is formed The rising area is longer and shallower than the falling, acting as a cutting edge area. In the present example, the length of the rising area is about three times the length of the sloping area. The sloping area has an angle of about 50 ° to the horizontal (ie to a plane that is perpendicular to the direction of rotation), while the rising area forms an angle of only about 12 ° to the horizontal. Between the rising and falling area an obtuse angle is formed, which in the present case is about 118 °. Both the sloping and the rising area are blade-like designed as a cutting edge. For this purpose, the self-opening sleeve tapers towards the cutting edge or runs toward the cutting edge in the manner of a blade. In the present case, this taper occurs only on the outside of the self-opening sleeve. The inner surface of the self-opening sleeve, however, is cylindrical in the region of the cutting edge. As a result, the cutting edge displaces the cut material outwards during cutting and thus contributes on the one hand to a clean cut.

In the example of FIGS. 11 to 13 There are a total of four cutting and / or piercing elements 32a-32d, which are followed by a single hold-down 35. The cutting elements 32 are all the same size and formed the same shape. The hold-down 35 is also approximately the same width or long, but has no cutting tip and is thus smaller. The distance from the hold-down element 35 to the first cutting and / or piercing tooth 32 in the direction of rotation is greater than the spacing of the teeth 32 from one another.

An advantage of these two embodiments is that they no longer need to be positioned accurately on the predefined spout opening. Thanks to their relatively long in the direction of rotation of the sleeve 3 or wide cutting and / or piercing elements, they can also contact the section spaced from the perforation and still exert enough pressure to release the portion D of the package. Furthermore, thanks to these elements, a relatively steep thread between the sleeve 3 and spout 10 can be selected, so that a rotation of less than 360 °, in particular of 300 ° is sufficient to open the shutter and press down the section D.

In FIG. 5 is shown a possibility of producing such a closure. The lid is sprayed separately, but the sleeve 3 and the spout part 2 become made in one piece. In this case, the sleeve 3 projects above part of the spout 2 out, being connected via connecting webs 5 with the spout part 2. If the part is injected, the sleeve 3 is completely pressed into the spout 20, wherein the connecting webs 5 break.

In the FIGS. 7 to 10 is a preferred embodiment of a Erstöffnungskennzeichnung shown. This type of marking can be used not only with this closure but with all closures, which have a spout with flange and a screw on the spout cover.

On the top of the flange 13, starting at the spout 10, a plurality of webs 15 are formed, which are parallel to a tangent to the spout 10 and parallel to each other. Their free ends are preferably on a common circle, which runs concentrically to the outer circumference of the spout 10. One or more webs 15, here two, can also run perpendicular to the other webs 15. This is in FIG. 10 recognizable. The free ends form undercut retaining tabs 15 'as shown in FIG FIG. 9 is apparent.

As in FIG. 7 shown, the guarantee strip 4 is sprayed on predetermined breaking bridges 23 on the cap 2, wherein it preferably completely surrounds the cap 2. In the never opened state of the closure, the retaining webs 40 of the guarantee strip 4 with the retaining lugs 15 'are engaged and prevent mutual rotation of the cap 2 and spout part 1, as in FIG. 10 is recognizable. When turning the cap 2, the predetermined breaking bridges 23 are released by axial tension and the guarantee strip is completely detached from the cap 2.

Preferably, connecting bridges 6 between cap 2 and guarantee strip 4 are still present, which are preferably wider than the webs 23. They are preferably distributed uniformly over the circumference of the cap, as for example in FIG. 8 is recognizable. In the example shown here, there are three such bridges 6, but their number may vary. These bridges facilitate and shorten the injection molding process, since relatively much material can be transported over these bridges. After making the cap and preferably before mounting the closure these bridges 6 are broken. Preferably, they are cut through with a knife or a laser beam. Such connection bridges can be used in all embodiments. They can also be used for all parts, which are sprayed together. This manufacturing method is not limited to the inventive closures described herein.

Further forms of the self-opening sleeve 3, in particular of the cutting and piercing elements are possible. The number of teeth can also be varied. Furthermore, the above-mentioned external and internal threads may be continuous or only partial thread.

LIST OF REFERENCE NUMBERS

1

pouring

10

pouring spout

12

external thread

13

flange

14

inner thread

15

web

15 '

Retention tab

2

screw cap

20

cover surface

21

shell wall

22

inner thread

23

Predetermined breaking points

24

takeaway

26

sealing lip

3

self-opening

30

ring

31

external thread

32a

first piercing element

32b

to

32e

second to fifth piercing element

33

distance

34

second cutting tooth

35

Retaining tooth

36

stop element

4

guarantee strip

40

Retaining web

5

connecting web

6

connecting bridge

K

cardboard package

D

section

Claims (15)

1. A plastic closing device comprising
   a pouring part (1) for fixing onto a packaging,
   a screw cap (2) adapted to be screwed onto the pouring part (1), and
   a self-opening collar (3) adapted to be moved downwards in the pouring part (1) towards the packaging with a screw action for opening the packaging,
   wherein the screw cap (2) comprises at least one driver (24), which acts on at least one stop element (36) of the self-opening collar (3) and which causes the self-opening collar (3) to move within the pouring part (1) into a lower position towards the packaging in order to open said packaging when the screw cap (2) is first opened, the self-opening collar (3) remaining in its lower position when the pouring part (1) is subsequently closed by means of the screw cap (2), and
   wherein the self-opening collar (3) comprises at least two downwards-projecting cutting and/or piercing elements (32a-32e) arranged along a periphery of the self-opening collar (3) and forming a lower edge thereof,
   wherein the cutting and/or piercing elements (32a-32e) have a substantially rectangular form, wherein a downwardly projecting longitudinal edge interrupts the rectangular form and forms a downwardly projecting triangle, thus creating a downwardly projecting tip, and wherein the longitudinal edge has, at its front relative to the direction of rotation of the collar (3), a portion that declines downwards and a portion which subsequently rises again,
   characterised in that the rising portion is longer and less steep than the declining portion.
2. The closing device according to claim 1, wherein the rising portion of the longitudinal edge has a length that is at least 2.5 times the length of the declining portion.
3. The closing device according to claim 1 or 2, wherein an obtuse angle is present between the rising portion and the declining portion of the longitudinal edge.
4. The closing device according to one of claims 1 to 3, wherein the downwardly projecting longitudinal edge forms a cutting edge at least in its declining portion.
5. The closing device according to claim 4, wherein the downwardly projecting longitudinal edge forms a cutting edge in its declining portion as well as in its rising portion.
6. The closing device according to claim 4 or 5, wherein the cutting edge is provided on an inner peripheral surface of the self-opening collar.
7. The closing device according to one of the preceding claims, wherein the cutting and/or piercing elements project downwards to the same extent.
8. The closing device according to one of the preceding claims, wherein the cutting and/or piercing elements (32a-32e) are arranged along the periphery so as to be distributed at the same distance.
9. The closing device according to one of the preceding claims, wherein the self-opening collar (3) comprises four to six, in particular five cutting and/or piercing elements (32a-32e).
10. The closing device according to one of the preceding claims, wherein the self-opening collar (3) comprises at least one hold-down element (35), which forms the lower edge together with the cutting and/or piercing elements (32a-32e).
11. The closing device according to claim 10, wherein the self-opening collar (3) comprises three to five, in particular four cutting and/or piercing elements (32a-32d) and one hold-down element (35).
12. The closing device according to one of the preceding claims, wherein the self-opening collar (3) comprises an external thread (31), which cogs with an internal thread (14) of the pouring part (1) so that the self-opening collar (3) rotates during its downwards movement.
13. The closing device according to claim 12, wherein the external thread has a pitch chosen in such a manner that the self-opening collar performs a rotation of less than 360 degrees in response to the unscrewing of the screw cap.
14. The closing device according to one of the preceding claims, wherein a single driver (24) is provided.
15. The closing device according to one of claims 1 to 14, wherein bars comprising projecting lugs (15'), which run parallel to a tangent of a pouring spout (10) are provided on a flange (13) of the pouring part (1), with which bars (15) of a tamper-proof strip (4), which is connected to the cap (2) and which at least partially surrounds said cap (2), engage.

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