EP0737156B1 - Plastic snap closure with a warranty seal and method for its production - Google Patents

Abstract

PCT No. PCT/CH95/00248 Sec. 371 Date Jun. 14, 1996 Sec. 102(e) Date Jun. 14, 1996 PCT Filed Oct. 23, 1995 PCT Pub. No. WO96/14252 PCT Pub. Date May 17, 1996The plastic snap closure possesses a snapping means (3) on the inside surface of the cap wall (2), said snapping means being able to be snapped over a bead on the container mouth. In order to display initial opening of the closure, approximately vertical weakened zones (4) are provided on the lower edge of the closure cap. The cap wall (2) will tear on initial opening of the snap closure in the area of at least one of these weakened zones (4).

Description

The invention relates to a plastic snap lock according to the features in the preamble of claim 1 and a Process for its production. Snap locks this Kind are used for closing containers, which on the outside of its approximately cylindrical mouth region have a circumferential bead. A main area of application is the closing of beverage bottles, e.g. Beer or Mineral water bottles.

Containers of this type are often made with crown caps Metal closed, which with the help of suitable folding devices be attached. When the container is closed the folded cap wall overlaps the bead at the container mouth. Such a closure is opened by bending the cap wall sideways with the help of a conventional cap lifter. This leads to a plastic one Deformation of the cap wall, the metallic crown cap can therefore no longer after opening the container for the first time be reliably closed.

EP-21 036 has therefore already been proposed instead the metallic crown cap is made of synthetic resin Capsule to use, which on the container mouth can be snapped on. The resin cap has for this purpose on your inner circumference a projecting waistband, which at sealed container the bead at the container mouth overlaps so as to seal the bottle. The closure is also opened with a conventional cap lifter; because the cap is made of elastic Material, it can be used in contrast to metallic crown cap without plastic deformation of the Remove the cap wall from the container mouth. The cap wall is only elastically expanded and opened when opened then return to their original shape. The cap can therefore be used repeatedly and the Quality of the seal of the closure will also depend on repeated opening and closing again are not impaired.

Aside from their qualities, caps are used in Regarding the sealing of the container, often requested that the first time you open the container in Obviously display and thus a guarantee function fulfill. EP-21 036 proposes that Reduce the thickness of the cap wall in its lower area, so that at this point when you open the container the gripper tooth of the cap lifter is deformed. Through this Deformation is shown when the container is opened for the first time. The quality and reliability of this guarantee function is largely of the type used Cap lifter dependent. A cap lifter with a narrow one Gripping tooth, e.g. with those contained in pocket knives Cap lifter used leads to a significant injury the lower edge of the cap wall. Usually have the cap lifters used to open metallic crown caps however a rather wide gripping tooth, with which the in the Plastic cap of a container described in EP-21036 can be removed without the cap wall being more obvious Way to hurt. The deformation caused by the gripping tooth the cap wall can come back after opening largely regress, so the guarantee function does not is reliably guaranteed.

Another option is to open a container for the first time Display snap lock, shown in GB-A-920 937. A closure cap is slotted in an area of the locking beads. By This weakening breaks said locking bead when it is opened for the first time in a clearly visible way.

It is an object of the invention to provide the guarantee function to improve known snap locks and a plastic snap lock to create the first time Open reliably and clearly visible.

According to the invention, this object is achieved by a plastic snap lock having the features of claims 1 and 1 Process for its production with the features of the claims 13 or 15 solved.

On the inner surface of the cap wall are along the circumference protruding, which can be snapped over a bead on the container mouth Locking means arranged. The radial thickness of this locking means reached in an annular locking area of the cap wall a maximum. When assembling the cap is in pressed axially onto the container mouth. The cap wall is expanded elastically and the locking means the cap slide over the bead at the container mouth. As soon as the annular rest area and thus the thickest point of the locking means has overcome the bead, snaps the cap onto the container mouth. Below of the rest area, the cap wall has at least three arranged around the circumference, approximately vertically running Zones of weakness where the strength of the Cap wall is reduced. As a rule, the Attenuation zones through an at least partial reduction the wall thickness, e.g. through vertical running notches, formed.

Tearing of the cap wall in the area of a weakening zone becomes particularly obvious because the cap wall in the Area of the weakened zone has a smooth outer surface. This can e.g. be achieved when the weakening zones by provided on the inner surface of the cap wall Depressions are formed.

The greatest forces act when opening the snap lock at the bottom of the cap wall. Tearing in the area The weakening zones are therefore favored if these extend to the lower edge of the cap wall.

To remove the cap from the container mouth a lifting tool must be attached to the lower edge of the cap. The resulting load on the cap wall leads to that the cap wall is in the range of at least one of the Weaken zones of weakness. Experienced by this tearing the cap wall permanent damage, which is the first time Opening of the cap shows clearly visible.

The quality of the snap lock in terms of its Tightness is primarily due to the strength of the Depending on the inner surface of the cap wall protruding locking means. To maintain the original quality of the seal even when it is renewed Close the container after opening it for the first time to ensure the strength of the cap wall in the annular locking area are not affected. The vertical weakening zones are for this reason arranged below the rest area so that the strength the rest area is not affected even if the cap wall in the range of one or more Zones of weakness torn.

They are also preferred for opening the snap lock for opening metal crown caps usual cap lifters used, the gripping tooth engages on one side on the cap wall. The cap wall must be opened the first time Tear the snap lock in any case, regardless of which point on the circumference of the cap the Cap lifter is attached. To ensure this requires at least three vertically running weakening zones, which are arranged distributed over the circumference. Prefers however, there will be a larger number of weakening zones used.

The cap wall tears in the area of the weakened zones even with slight force. Without the guarantee function can affect the snap lock therefore be designed so that it is relatively small Force is removable from the container mouth. At a preferred embodiment are used as locking means several on the inner surface of the cap wall along the circumference arranged locking elements used, which by spacing are separated from each other. This configuration has opposite a circumferential locking bead has the advantage that the cap wall in the space between successive locking elements is more elastic and flexible. This will reduce the force required to lift the snap lock reached.

Another improvement arises when the weakening zones in the space between successive locking elements to be ordered. The weakening zones are located thus in an area of the cap wall that does not pass through locking elements provided on the inner surface is reinforced. There these areas especially when opening the snap lock the cap wall will tear due to the weakening zones arranged in this area additionally favored.

It is preferred to open the snap lock, one too Cap lifter that can be used to remove metal crown caps used. Cap lifters of this type have a gripping tooth, the the lower edge of the cap wall at a point of the Extends underneath and one connected to the gripping tooth Support surface, which on the outside of the cap base is present and serves as an abutment. The distance between that Gripping tooth and the support surface is with most cap lifters matched to the relatively flat metal crown caps and is usually about 12-15 mm. The height of the cap is therefore in a preferred embodiment maximum 12 mm, so that the closure with a Cap lifter of the type mentioned can be opened.

There are special requirements for the strength of the cap wall posed. When opening the cap wall in the area of tear vertical weakening zones. This is done through in radial direction acting on the lower edge of the cap Forces reached. On the other hand, the simultaneous compression of the Cap wall undesirable in the axial direction, as the vertical Power component primarily for lifting the cap is needed. The axial compression of the cap wall The cap wall is preferably kept as small as possible designed their outer surface several over the circumference ribs arranged radially outwards having. Through these ribs, the axial load capacity the cap wall increased. Because that was caused by a cap lifter Load is greatest at the bottom of the cap, the ribs are preferably designed so that they are up to extend to the lower edge of the cap. This has at the same time the advantage that the for the gripper tooth of the cap lifter available cap in the lower edge of the cap Area of the ribs becomes larger. Attaching ribs to the cap wall leads to an increase in the wall thickness in the area of these ribs. The vertical zones of weakness, in whose area strives for the smallest possible wall thickness will therefore be preferred in the space between successive ones Ribs arranged.

A second way to improve the axial load capacity the cap wall is the lower, with weakened zones provided area of the cap wall from two concentric To shape ring elements. The cap wall is there thereby in their lower, with weakened zones Area from an inner support ring and a support ring surrounding, concentric to this arranged ring. The approximately vertical weakening zones become provided on the outer guarantee ring. So that is achieved that when opening for the first time, it is primarily the outer guarantee ring is destroyed and the more stable support ring the vertical Absorbs lifting forces of the cap lifter. The concentric Rings are therefore preferably designed so that only the outer guarantee ring has weakening zones, while the inner support ring is not weakened by weakening zones is and therefore has a much higher strength.

To ensure that the outer guarantee ring when you first Opening the lock actually destroyed a snap fastener of this type is preferred designed that the guarantee ring extends over the bottom of the support ring extends downward. The already principles explained above for the design of the weakening zones also apply in the event that this on a Guarantee ring of the type just described can be attached. The weakening zone is also preferred here by an indentation provided on the inner surface of the guarantee ring formed, with the guarantee ring in the area of the weakening zones has a smooth outer surface. This has the advantage that the tearing from the outside is immediately recognizable.

When dimensioning the guarantee ring and the interior Support ring are the different functions of this Wall elements to be considered. The are preferred Size ratios chosen so that the radial thickness of the Guarantee ring smaller than the radial thickness of the support ring is.

Also the connection between the individual wall elements can be designed differently. Wall elements are in this context three elements, namely the support ring, the guarantee ring surrounding the support ring and the upper part the cap wall, which in this context is also called a third ring element can be viewed and below is called a wall ring. When designing the Connections are again the function of the individual elements to consider. The support ring must be in the axial direction acting forces of the cap lifter on the upper wall ring (on which the snap elements of the snap lock are arranged) transferred. The support ring is therefore preferred designed as a direct extension of the upper wall ring, so that the support ring together with the top wall ring forms a continuous wall section. Light different diameters of support ring and wall ring are of course still possible, especially the outside diameter of the support ring compared to that of the wall ring preferably a little less space for the outside To create a guarantee ring.

The outer guarantee ring can be made in the same way as the Support ring also with the upper wall ring of the cap wall get connected. Alternatively, the guarantee ring also only by a plurality of distributed over the circumference arranged, elastic webs with the rest of the cap wall get connected. With the "rest of the cap wall" is the Wall ring and the adjoining support ring meant. The radial mobility becomes possible by the connection by means of webs of the guarantee ring further increased so that it the cap is opened for the first time is more easily pushed out and the vertical weakening zones thus tear faster.

The guarantor ring is joined by webs with the rest of the cap wall connected, these webs can also have a guarantee function take over: The connecting webs are like this designed that when opening it for the first time, some of these Tear off the webs. To enable tearing off, a Guarantee ring needed, whose inner diameter is larger than is the maximum outside diameter of the rest of the cap wall. The webs are preferred between the inner surface of the Guaranteed ring and the outer surface of the support ring arranged.

The force necessary to tear off the guarantee ring becomes determined by the number and thickness of the webs.

The weakening zones are preferably designed so that the Tear the cap wall in particular in the lower Area is clearly visible. According to the invention the weakening zone becomes like this designed that the outer surface of the cap wall a smooth Surface. There is a on the smooth outer surface Crack particularly easy to see. The cap wall tears particularly slightly on if they are in the upper area of the weakened zone is broken, so that between the breakthroughs and the lower edge of the cap wall tearable web is located. Located in the area of the footbridge again a smooth outer surface, because then a crack is particularly easy to recognize.

Particularly efficient and cost-effective production is achieved if the snap lock is made in one piece from plastic will be produced.

In addition to the initial assembly of the snap lock already mentioned at the beginning by snapping the cap onto the Other assembly methods are also conceivable, where the cap is placed on the Container mouth deformed by external heat and in is brought into its final form. This deformation can either by using a heat shrinkable plastic, or achieved by external force will. For example, an electrically heated pliers could are used, which the cap wall after the Put on the container mouth deformed. The weakening zones too can be retrofitted in this way will.

A simple variant for producing the above Snap lock is the whole Snap lock together with the vertically running weakening zones to cast in one operation. Depending on the shape However, the desired weakening zones can be an advantage be to attach the weakening zones later. For this purpose, a closure is first used in a casting process a cap bottom, a cylindrical one adjoining it Cap wall and along the inner surface of the cap wall the circumferential locking means made. Subsequently are in a further operation in the lower area of the Cap wall at least three approximately vertically extending weakening zones appropriate. The attachment of the weakening zones can e.g. with the help of a cutting tool by cutting or milling. Alternatively, it is also possible the weakening zones through subsequent hot forming or by melting, e.g. under use a heated tool. The attachment of the weakening zones can be done before or after putting on the cap on the container mouth.

An alternative method of making a Snap lock is first in a casting process made a cap, the cap wall several Has slits that extend vertically from their bottom edge extend upwards. These slots are made by deforming the cap wall and / or the filling of plastic material at least partially closed again, so that in the area the slits remain a zone of weakening of the cap wall. The plastic material filled into the slots can e.g. a liquid or pasty adhesive act, which then dries and hardens. It can however, it is also a thermoplastic, filled in the slots when heated and solidifies again when it cools down. The renewed departure of the slots during the assembly of the snap lock can be prevented in this embodiment by that the slots only after the snap lock assembly getting closed.

Figur 1

die Ansicht eines erfindungsgemässen Schnappverschlusses von unten,

Figur 2

eine Darstellung der Schnittebene A-A, in Figur 1,

Figur 3

die Schnittdarstellung einer durch einen Schnappverschluss verschlossenen Behältermündung mit angesetztem Kappenheber,

Figur 4

den Zustand der in Figur 3 gezeigten Anordnung nach dem Anheben des Schnappverschlusses,

Figur 5

die perspektivische Darstellung eines Schnappverschlusses nach dem erstmaligen Oeffnen,

Figur 6

die Seitenansicht eines Schnappverschlusses mit einer bevorzugten Alternative zur Gestaltung der Schwächungszonen,

Figur 7

einen auf eine Behältermündung aufgesetzten Schnappverschluss mit radial abstehenden Rippen an der Aussenfläche der Kappenwand,

Figur 8

die Ansicht der in Figur 7 gezeigten Verschlusskappe von unten,

Figur 9

den Randbereich eines Schnappverschlusses, dessen Kappenwand im unteren Bereich aus einem Stützring und einem Garantiering besteht,

Figur 10

einen Schnappverschluss mit einem Garantiering, der durch Stege mit dem Rest der Kappenwand verbunden ist, und

Figur 11

die Ansicht des in Figur 10 dargestellten Schnappverschlusses von unten.

The invention is explained in more detail below on the basis of exemplary embodiments. Show it:

Figure 1

the view of a snap lock according to the invention from below,

Figure 2

2 shows a representation of the sectional plane AA in FIG. 1,

Figure 3

the sectional view of a container mouth closed by a snap closure with attached cap lifter,

Figure 4

the state of the arrangement shown in Figure 3 after lifting the snap lock,

Figure 5

the perspective view of a snap lock after the first opening,

Figure 6

the side view of a snap lock with a preferred alternative to the design of the weakening zones,

Figure 7

a snap closure placed on a container mouth with radially projecting ribs on the outer surface of the cap wall,

Figure 8

the view of the closure cap shown in Figure 7 from below,

Figure 9

the edge area of a snap lock, the cap wall of which consists of a support ring and a guarantee ring in the lower area,

Figure 10

a snap lock with a guarantee ring, which is connected by webs to the rest of the cap wall, and

Figure 11

the view of the snap lock shown in Figure 10 from below.

FIG. 1 shows a snap closure according to the invention from below, with a view of the inner surface of the cap base 1. An the inner surface of the cap wall 2 are distributed over the circumference a plurality of locking elements 3 arranged, which when attached Snap lock a bead on the container mouth reach behind. The vertical weakening zones 4 are by notches 13 on the inner surface of the cap wall 2 formed, which in the space between successive Locking elements 3 are arranged.

Figure 2 shows a sectional view of the snap lock 1, the section plane runs along the in Figure 1 drawn level A-A. The notches 13 are provided on the inner surface of the cap wall 2, so that the Cap wall in the area of weakening zones 4 a smooth Has outer surface 17. The cap wall is tearing therefore particularly well recognizable from the outside. The notches 13 extend to the lower edge 14 of the cap wall 2.

Figure 3 shows the sectional view of a container mouth with attached snap lock. Reach behind the locking elements 3 a bead 5 of the container mouth. The ring-shaped Locking area 6, in which the radial thickness of the locking elements 3 their maximum reaches 7 is for the fastening of the cap on the container mouth particularly important. A weakening of the cap wall 2 in the area of the annular Rest area 6 would be the quality of the seal that can be achieved greatly decrease. The weakened zones formed by notches 13 4 are therefore below the annular locking area 6 of the cap wall 2 arranged.

A cap lifter 10 is also shown in FIG a position like that to open the container on the snap lock is scheduled. The gripper tooth 9 of the cap lifter grips under the lower edge of the cap at one point. The gripping tooth 9 is with a contact surface 18 of the Cap lifter connected, which on the outside of the cap base 1 is present. Since the distance 19 between the gripping tooth 9 and the contact surface 18 in conventional, also for opening of metal crown caps usually suitable cap lifters The plastic snap locks are also between 12 and 15 mm preferably designed so that its height is 12 is a maximum of 12 mm. Furthermore, it is for opening by means of a cap lifter if between the Inner surface of the cap wall and the outer surface of the container neck there is a distance 8 so that the gripping tooth 9 of the Cap lifter the lower edge of the cap wall as strong as possible can reach behind.

The cap lifter 10 shown in FIG. 3 becomes in the direction of the arrow 11 moves, so the gripping tooth 9 ultimately pressed against the underside of the cap wall causes the snap lock to unilaterally from the Container mouth is lifted. One in this state The arrangement is shown in FIG. 4. On that Where the gripping tooth 9 was against the cap wall this pressed outwards when opening. The cap wall was thereby in the area of the near the gripping tooth 9 Weakened zone 4 torn so that the first time opening the snap lock is immediately visible. At the in The example shown in FIGS. 3 and 4 is the gripping tooth 9 of the cap lifter just in the area of a weakening zone 4 the cap wall 2. The cap wall is in the area of the weakening zones 4 but so easily tearable that it Area of the closest weakening zones also torn if the gripping tooth of the cap lifter is in the middle between two neighboring weakening zones is applied.

Figure 5 shows the perspective view of a snap lock after opening for the first time. The cap wall 2 is torn open in the area of two vertical weakening zones 4a, such a picture emerges when the cap lifter when opening the closure between these two weakening zones 4a is applied. The cracks in the cap wall are unmistakable and ensure a reliable guarantee function.

Figure 6 shows the side view of an alternative embodiment a snap lock where the cap wall is broken in the upper area of the weakened zones. There is one below each of the breakthrough points 15 tearable web 16. This variant has the advantage that the part of the cap wall to be torn open on the web 16 and thus concentrated on the lower edge area of the cap wall is. Since the load occurring when opening the lower Is greatest at the edge of the cap wall, the webs 16 tear particularly quickly. This could be a further improvement achieved that the radial thickness of the webs 16 is reduced. This is benefited by an additional one Notch on the inner surface of the cap wall reached, so that the cap wall in the area of the web 16 is still has a smooth outer surface.

Figure 7 shows a placed on a container mouth Snap lock, the cap wall several over the circumference ribs distributed and radially outward having. In the left half of Figure 7 is the exterior view of the snap lock shown in the right Half a sectional view. With the elongated, about vertically extending ribs 20 on the outer surface of the Cap wall becomes an increased resilience of the cap wall in axial direction 7 reached. Since the ribs 20 to extend the lower edge of the cap wall, the available attack surface for attaching a cap lifter enlarged. This can also be seen in FIG. 8, in which the closure cap according to Figure 7 in a Bottom view is shown. The vertical ones Weakening zones 4 are each in a space between two adjacent ribs 20 are arranged. The Attenuation zones 4 are caused by notches on the inner surface the cap wall formed. In the space between adjacent ribs 20, the cap wall has a smooth outer surface, so tearing a weakening zone from is easily recognizable from the outside.

Figure 9 shows the sectional view of the edge region of a Cap, the cap wall in its lower, with Weakening zones 4b provided area from a support ring 21st and a concentric to the support ring surrounding it arranged guarantee ring 22 exists. The weakening zones 4b are provided on the outer guarantee ring 22. This are by notches 13a on the inner surface of the guarantee ring formed so that the guarantee ring in the area of Weakening zones keeps a smooth outer surface and that Tearing a weakened zone is easily recognizable. Of the Guarantee ring 22 extends over the lower edge of the Support ring 21 downwards. This ensures that the guarantee ring 22 from a conventional cap lifter, which is usually on the inner edge of the support ring 21st intervenes (see also Figure 3) can still be detected. The radial thickness 24 of the guarantee ring 22 is essential smaller than the radial thickness 25 of the support ring 21. Thus the fact that the guarantee ring 22 should be as fragile as possible, the inner support ring 21st however, transfer the lifting force exerted by a cap lifter should and therefore needs a certain strength.

The cap wall of this snap closure points next to the inner support ring 21 and the outer guarantee ring 22 still an upper wall area where it is taken in the bottom is also an annular section which hereinafter referred to as wall ring 26. The The cap wall therefore basically consists of three ring elements, which are interconnected. The one shown in Figure 9 Support ring 21 represents a direct continuation of the upper one Wall ring 26 represents, the two ring elements have the same Inside diameter. The outer guarantee ring 22 is from that inner support ring 21 by a likewise annular Space 28 separated. Will the entire cap cast in one piece from plastic, this is ring-shaped Gap 28 necessary for manufacturing reasons. The outer diameter of the wall ring 26 increases at its the outer diameter of the guarantee ring 22 at the lower end, so that the guarantee ring (as well as the support ring 21) is connected at the end to the upper wall ring.

Figure 10 shows an alternative embodiment for a snap lock with support ring 21a and guarantee ring 22a. Here is the inside diameter of the guarantee ring 22a larger than the maximum outside diameter of the rest of the Cap wall. The guarantee ring 22a is unique of elastic arranged around the circumference Web 23 connected to the rest of the cap wall. The expression "Rest of the cap wall" is summarized here for the inner support ring 21a and the upper wall ring 26. In the example shown, the webs 23 are between the Inner surface of the guarantee ring 22a and the outer surface of the Support ring 21a arranged.

Finally, in Figure 11 is the bottom view of a snap lock shown in Figure 10. It should be noted that in this exemplary embodiment, the same number of webs 23 and vertical weakening zones 4c of the guarantee ring 22a are provided, each between two vertical Attenuation zones 4c a connecting web 23 is arranged.

Claims (17)

1. A plastics snap closure for containers with a substantially cylindrical mouth region, comprising a cap end portion (1) and a cap wall (2) which adjoins same and on the inside surface of which are arranged retaining means (3) which project along the periphery and which can be snapped over a bead (5) on the container mouth and the radial thickness of which reaches a maximum (7) in an annular retaining region (6) of the cap wall, characterised in that vertically extending weakening zones (4) which are formed by recesses (13) are arranged on the inside surface of the cap wall (2), that the weakening zones (4) are arranged beneath the retaining region (6) and extend to the lower edge (14) of the cap wall (2), and that the cap wall has a smooth outside surface in the region of the weakening zones (4).
2. A snap closure according to claim 1 characterised in that the retaining means are a plurality of retaining elements (3) which are arranged along the periphery at the inside surface of the cap wall and which are separated from each other by spacings.
3. A snap closure according to claim 1 characterised in that the weakening zones (4) are arranged in the intermediate space between successive retaining elements (3).
4. A snap closure according to one of claims 1 to 3 characterised in that the cap wall (2) is perforated in the upper region of the weakening zones (4) so that a respective tearable bridge portion (16) is disposed between the perforation locations (15) and the lower edge of the cap wall.
5. A snap closure according to one of claims 1 to 4 characterised in that the outside surface of the cap wall has a plurality of radially outwardly projecting ribs (20) which are arranged in a distributed configuration over the periphery and which extend to the lower edge of the cap.
6. A snap closure according to claim 1 characterised in that in its lower region which is provided with weakening zones (4b, 4c), the cap wall comprises an inner support ring (21) and an anti-tamper ring (22) which surrounds the support ring and which is arranged concentrically with respect thereto, and that the weakening zones are provided on the anti-tamper ring (22).
7. A snap closure according to claim 6 characterised in that the anti-tamper ring (22) extends downwardly beyond the lower edge of the support ring (21).
8. A snap closure according to one of claims 6 and 7 characterised in that the weakening zones (4) are formed by recesses (13a) provided on the inside surface of the anti-tamper ring (22) and the anti-tamper ring has a smooth outside surface (17a) in the region of the weakening zones.
9. A snap closure according to one of claims 6 to 8 characterised in that the radial thickness (24) of the anti-tamper ring is less than the radial thickness (25) of the support ring.
10. A snap closure according to one of claims 6 to 9 characterised in that the anti-tamper ring (22a) is connected to the remainder of the cap wall solely by a plurality of elastic bridge portions (23) which are arranged in a distributed configuration over the periphery.
11. A snap closure according to one of claims 6 to 10 characterised in that the inside diameter of the anti-tamper ring (22a) is larger than the maximum outside diameter of the remainder of the cap wall.
12. A snap closure according to one of claims 1 to 11 characterised in that the height (12) of the closure cap is a maximum of 12 mm so that the closure cap can be removed from a container mouth by a bottle opener which can also be used for removing metal crown caps.
13. A method of manufacturing a snap closure according to one of claims 1 to 12 characterised in that firstly a closure having a cap end portion (1), a cylindrical cap wall (2) adjoining same and having retaining means (3) projecting along the periphery at the inside surface of the cap wall is produced in a casting operation, and that then at least three substantially vertically extending weakening zones are produced in the lower region of the cap wall, wherein the weakening zones (4) are disposed beneath the retaining region (6) and extend to the lower edge (14) of the cap wall (2) and the cap wall (2) has a smooth outside surface in the region of the weakening zones (4).
14. A method according to claim 13 characterised in that the vertical weakening zones are produced by means of a cutting tool by cutting or milling and/or by heat deformation or melting.
15. A method of manufacturing a snap closure according to one of claims 1 to 12 characterised in that firstly a closure having a cap end portion (1) and a cylindrical cap wall (2) with retaining means on the inside surface thereof is produced in a casting operation, wherein the cap wall has a plurality of slots which are arranged beneath the retaining region and which extend vertically upwardly from the lower edge thereof and that the slots are at least partially closed again by deformation of the cap wall and/or by filling with plastics material so that a weakening zone of the cap wall remains in the region of the slots and the cap wall has a smooth outside surface.
16. A method according to claim 15 characterised in that the slots are closed only after fitting of the snap closure.
17. A method according to one of claims 15 and 16 characterised in that a liquid or pasty filling material which hardens after some time is introduced into the slots, to close the slots.

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