WO2003084833A1

WO2003084833A1 - Container screw-closure cap

Info

Publication number: WO2003084833A1
Application number: PCT/EP2002/012630
Authority: WO
Inventors: Hans Umiker
Original assignee: PLAMATEC AG
Current assignee: PLAMATEC AG
Priority date: 2002-04-05
Filing date: 2002-11-12
Publication date: 2003-10-16
Anticipated expiration: 2004-10-05
Also published as: EP1492713A1; AR037657A1; AU2002351976A1; ATE334067T1; DE60213480D1; EP1492713B1

Abstract

The invention provides a container screw-closure cap (1) which is made of plastic and is provided, on the inner side of its cap base (4), with an annular sealing lip (7) which, when the screw-closure cap (1) is screwed onto the container mouth (2), seals against the cylindrical inner side (2') of the container mouth (2), it being the case that the annular sealing lip (7), which has a predetermined bending strength, at a radial spacing in the outward direction, is assigned a double annular rib (8, 8', 8') which extends away from the inner side of the cap base (4) with a downwardly double tapering (8', 8') cross section and with a smaller height than the sealing lip (7) and engages with the end side of the container mouth (2) when the screw-closure cap (1) is screwed on, and that extending away from the transition region of the cap base (4) into the lateral cap surface (3) is another annular rib (9), with tapering cross section, which acts in a sealing manner on the outer side of the container mouth (2).

Description

Container Screw-Closure Cap

The invention relates to a container screw-closure cap which is made of plastic and is provided, on the inner side of its cap base, with an annular sealing Up which, when the screw-closure cap is screwed onto the container mouth, seals against an inner side of the container mouth.

In the case of known screw-closure caps of this type, which are used, for example, for bottles, the annular sealing lip engages in a sealing manner with the inner edge of the container mouth. It has been found in practice that the sealing action of the annular sealing lip is not sufficient in many cases, in particular on account of a deformation of the cap base under the internal pressure of the container. Moreover, even in the case of new containers which are filled for the first time, but in particular in the case of refilled containers, the container mouths may exhibit irregularities or damage which counteract(s) satisfactory sealing of the container.

The object of the invention is thus to provide a screw-closure cap which has an annular seal on the cap base which seals against an inner side of a container mouth and in the case of which the problems outlined are avoided and by means of which satisfactory sealing is ensured even in the case of the container being reclosed and in the case of irregularly formed mouths.

The screw-closure cap according to the invention is distinguished in that the annular sealing lip, which has a predetermined bending strength, at a radial spacing in the outward direction, is assigned a double annular rib which extends away from the inner side of the cap. base with a downwardly double tapering cross section and with a smaller height than the sealing lip and engages with the end side of the container mouth when the screw-closure cap is screwed on, and in that extending away from the transition region of the cap base into the lateral cap surface is another annular rib, with tapering cross section, which acts in a sealing manner on the outer side of the container mouth. The double annular rib, on its end side, has two spaced-apart annular protrusions.

By virtue of this end side and outer side sealing region extending over a right angle, the cap base is bowed (doming effect) in the event of a build-up in pressure of the medium in the container, the lever action resulting in an additional pressure being exerted on the outer and radial sealing region of the container mouth and in an increase in the contact pressure per unit surface area. It is precisely on account of the wide range of different types of damage in this region of the container mouth that this seal design performs an additional important function specifically for use in the dnhks industry.

According to a preferred embodiment of the invention, the annular rib, which acts on the outer side of the container mouth, is preferably of essentially N-shaped design in cross section.

The invention is explained in more detail hereinbelow by way of exemplary embodiments and with reference to the accompaning drawings in which:

Fig. 1 shows ah axial section through a screw-closure cap, with a tamper evidence band for returnable bottles, having four sealing elements according to the invention; Fig. 2 shows a bottom view onto the tamper evidence band^" of the sealing cap according to Fig. 1; Fig. 3 shows an axial section through the tamper evidence band of Fig. 2; Fig. 4 shows an axial section through a screw-closure cap, with a tamper evidence band for disposable bottles, having four sealing elements according to the invention; Fig. 5 shows a bottom view onto the tamper evidence band of the cap according to Fig. 4; Fig. 6 shows an axial section through the tamper evidence band of Fig. 5; and Fig. 7 shows an enlarged axial section through part of the caps, namely through the sealing elements according to the invention.

Referring to Figs. 1, 4 and 7 together, there is shown a screw-closure cap 1 (illustrated only in part in Fig. 7), which is produced from plastic, e.g. by injection moulding or compression moulding. The cap 1 is intended for mounting on a container mouth 2, and has a lateral surface 3 and a base 4. The lateral cap surface 3 bears, on its inner side, a thread 6 via which the screw-closure cap 1 can be screwed onto a mating thread 5 on the outer side of the container mouth 2.

The base 4 of the screw-closure cap 1 bears on its inner side, in the region of the inner edge 2" of the container mouth 2, an annular sealing Up 7, which projects integrally downwards from the base 4 and in axial section, in the non-deformed state, has a substantially vertical inner side 7', a radially outwardly curving top outer- wall section and a conically downwardly and inwardly running bottom outer-wall section.

In the embodiments shown in Fig. 1, 4 and 7, the annular sealing lip 7, by way of its outher-wall sections (obliquely inwardly running conical outer-wall section and curved outer- wall section), comes into contact with the inner edge 2", before the thread engagement, when the screw-closure cap 1 is screwed on and, when it penetrates into the cylindrical inner side 2" of the container mouth 2, is deformed by compression such that a relatively wide annular zone is produced as a sealing surface in relation to the inner side 2" of the container mouth 2. In the case of the material of the screw-closure cap having a predetermined level of rigidity, the contact and/or sealing pressure per unit surface area is reduced as a result.

At a radial spacing from the annular sealing lip 7, a double annular rib 8 extends away from the base 4 of the screw-closure cap 1, said double annular rib 8 being of a considerably smaller height than the annular sealing lip 7 and acting on the end side of the container mouth 2 via two annular protrusions 8', 8". At right angles to the annular rib 8, in addition, a further annular rib 9 is provided from the transition region of the cap base 4 into the lateral cap surface 3, said further annular rib 9 acting on the outer side of the container mouth 2 and being designed to taper in an essentially V- shaped manner in cross section. By virtue of this right-angled sealing zone 8, 9, the cap base 4 is bowed (doming effect) in the event of a build-up in pressure of the medium within the closed container. Consequently, an additional pressure is exerted on the radially outer sealing region 8 "of the container mouth 2 and the sealing rib 9 as a result of lever action, which means that there is an increase in the contact pressure per unit surface area in this region. It is on account of the wide range of different types of damage in this region of the container mouth 2 that the screw cap 1 according to the invention performs an additional important function, specifically for use in the drinks industry. The screw cap 1 according to the invention is preferably produced from plastic by injection moulding or by compression moulding.

To summarize the essential features, the container screw-closure cap 1 is made of plastic, preferably polyethylene, and has four sealing elements.

The main sealing element is the tongue-like sealing lip 7 which engages a sealing contact border in the inner side of the container 2. A second extension 9 seals the container on the outer side. A fixed stop 8 with annular protrusions 8' and 8" is located on the top border of the container 2. Said annular protrusions are of different heights. The inner annular protrusion 8' is higher than the outer protrusion 8".

By virtue of an increase in pressure in the container, the cap base 4 bows in a domelike manner. The inner seal 7 moves away from the container wall 2". At the same time, the annular protrusion 8' lifts up slightly, but the outer side of the cap 1 presses more in the direction of the center of the container 2 and the extension 9 and the annular protrusion 8" is thus pressed to a more pronounced extent against the container mouth 2 and, in the process, seals the closure 1 again on the top out side of the container 2 and via the extension 9.

A tamper evidence band (Fig. 2, 3 or Fig. 5, 6, respectively) is fixed to the base body 1 by means of weak bridges 13. A wraparound projection element 14 snaps on an overhang at the lower end of the bottle outlet 2. The shaping of the wraparound projection element 14 guarantees the function of the tamper evidence band. After the bottle 2 has been opened the band remains on the container 2 (Fig. 4 to 6) or the band remains on the cap body 1 (Fig. 1 to 3).

The described sealing system 7, 8, 9 of the closure cap 1 is applicable for disposable containers as well as for returnable containers. The outer diameter of the bottle neck 2 having the screw thread 5 at the container mouth 2 is standardized, so that the outer sealing 9 and the double annular rib 8 of the closure cap 1 may have the same dimensions, regardless whether a non-returnable bottle or a returnable bottle is to be closed: It is only the wall thickness and, thus, the clear opening 2" of the bottle neck 2 that may differ. This difference is taken into account by forming the inner seal 7 further inwards or further outwards with respect to the cap base 4. In other words, the position of the inner seal 7 is designed such that its spacing from the outer seal 9 increases as the clear opening 2" of the bottle neck 2 decreases.

However; the tamper evidence band (Fig. 2, 3) of a closure cap for returnable bottles (Fig. 1) has a more complex design than the tamper evidence band (Fig. 5, 6) of a closure cap belonging to a non-returnable bottle (Fig. 4). The tamper evidence band, in the case of returnable containers, is to break off at only part of the circle (crack point 12 in Fig. 2) and shall remain connected to the cap 1 at the residual part of the circle. In accordance with such purpose, the sealing system 7, 8, 9 and the tamper evidence band of such a closure cap are tuned as described below. The point is to close a filled bottle by the closure cap 1 in such a way that neither the sealing system 7, 8, 9 nor the tamper evidence band (Fig. 1 to 3) are damaged.

The counter screw 6 of the closure cap 1 which is adapted to the standardized container 2 is drawn downwards to a relatively large extent (Fig. 1). When the cap 1 is going to close the filled bottle 2, an intervention of the screw 6 occurs before the inner seal 7 touches the bottle neck 2 and before the tamper evidence band 10-14 touches the pilfer proof ring of the bottle 2. Only after the screw 6 has performed approximately a half turn so that the axis of the closure cap 1 is aligned with the axis of the bottie neck 2, the first snap-on of the tamper evidence band 10-14 occurs at the pilfer proof ring. In this manner, the crack point 12 of the tamper evidence band 10-14 is guarded against premature extension. The tamper evidence band is, on a part of the circuit, fixed to the cap body 1 by week bridges 13. The band grips below the pilfer proof ring of the bottle neck 2, although the protrusion 14 of the tamper evidence band (Fig. 1-3) does not have the same form all along the circle. The tamper evidence band is designed such that the consumer may immediately recognize the occurrence of a first opening. On the other hand, no part of the tamper evidence band remains at the bottle neck because the bottle shall be cleanly re-usable.

In order to guarantee such functions, the tamper evidence band has several crescent- shaped cams 11 gripping under the piifer proof ring of the bottle. Preferably three such cams i 1 are arranged in the vicinity of the crack point 12 of the tamper evidence band. The cams 11 are provided with a sharp-edged upper surface and have a tapering extension downwards to be able to slide over the pilfer proof ring of the bottle neck 2.

Stretch windows 10 are arranged between the cams 11. The stretch windows 10 extend like narrow stripes in vertical direction and close in re-inforcements at the lower edge of the band. The stretch windows 10 are designed to lessen the material of the tear-off part of the tamper evidence band. The longish notches 10 extend downwards at the outer circle (Fig. 2) and at the opposite location of the inner circle (Fig. 3). The stretch windows 10 at the inner side when approaching the lower edge of the tamper evidence band, pass into the re-inforcements (Fig. 3). In this way, the tamper evidence band does not tear off at its iower edge (apart from the crack point 12), but may be stretched in the upper part where the cams 11 are located. It is by this design that the caps 1 may be screwed on without damaging the crack point 12, while the cams 11 are interlocking at the first opening thus tearing off the crack point 12.

It goes without saying that the exemplary embodiment shown may be modified in various ways within the context of the idea of the invention, in particular as far as the configuration of the double rib 8 and the further rib 9 is concerned. List of Reference Numbers

1 screw-closure cap

2 container mouth

2" cylindrical inner edge of container mouth 2

3 lateral cap surface 4^" cap base

5 thread on the container mouth 2

6 thread on the lateral cap surface 3

7 annular sealing lip

V vertical inner side of annular sealing lip 7

8 double annular rib

8 ' inner annular protrusion

8" outer annular protrusion

9 outer annular rib

10 stretch windows

11 crescent-shaped cams

12 crack point

13 weak bridges

14 cross section for gripping under the pilferproof ring of the container

Claims

1. Container screw-closure cap which is made of plastic and is provided, on an inner side of a cap base, with an annular sealing lip having a form such that, when the screw-closure cap is screwed onto a container mouth, said lip seals against an inner side of the container mouth, the cap further comprising a double annular rib which extends away from the inner side of the cap base with a downwardly double tapering cross section each with a height smaller than that of the sealing lip, such that the double annular rib has two spaced-apart annular protrusions for engaging with an end of the container mouth when the screw-closure cap is screwed on, and a further annular rib extending away from a transition region between the cap base and a cap side, said further annular rib having a tapering cross section for acting in a sealing manner on an outer side of the container mouth.

2. Screw-closure cap according to Claim 1, characterized in that the annular rib, which acts on the outer side of the container mouth, is of essentially V-shaped design in cross section.

3. Screw-closure cap according to claim 1 or 2, characterized by a circular tamper evidence band having weak bridges, having protruding cams for snapping on an overhang of the bottle mouth and having stretch windows between said cams on part of the circle in the vicinity of a crack point, so that the tamper evidence band remains at the cap body when the container is opened.

4. Screw-closure cap according to claim 1 or 2, characterized by a circular tamper evidence band having weak bridges and having protruding elements snapping on an overhang of the bottle mouth so that the tamper evidence band remains at the container when the container is opened.