GB1577705A - Pilferproof closures for bottles jars and like containers - Google Patents

Description

(54) PILFERPROOF CLOSURES FOR BOTTLES, JARS AND LIKE CONTAINERS (71) We, U.G. CLOSURES & PLASTICS LIMITED, a British Company of Kingston Road, Staines, Middlesex, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pilferproof closures for bottles, jars and like containers, and in particular to a metal pilferproof closure of the kind consisting of a top and a skirt which comprises an upper part, capable of having a thread formed therein, and a sealing band which is adapted to be separated from the upper part along a circumferential weakening line formed by slits connected by spaced bridges. Such a closure is referred to herein as " a closure of the kind described".

In a closure of the kind described, when a sufficient torque is applied to the skirt by unscrewing the closure of a sealed bottle or container, the bridges rupture and break, visibly indicating that there has been access to the bottle or other container.

The upper part of the skirt, together with the integral top, forms a re-closure, which may be screw-threadedly attached to the container to re-seal it. One disadvantage of such closures is that, when the sealing band has been separated from the re-closure element the latter has an uneven free edge caused by the fact that portions of the bridges forming the frangible weakening line still remain attached thereto. These remaining bridge portions, or traces, can cause damage to the hands of a user, and it is an object of the present invention to provide means whereby such traces are eliminated from the re-closure element of a closure of the kind described.

According to the invention, therefore, in a closure of the kind described each bridge in the circumferential weakening line is weakened across its width substantially along a line joining the upper corners of the adjacent slits.

The weakening of the bridges may involve the cutting and compression of the metal forming the upper part of the bridge, or simply the deformation thereof radially inwardly relatively to the remainder of the skirt of the cap. The weakening of the bridges is suitably carried out simultaneously with the cutting of the skirt of the cap to form the weakening line of slits.

The drawings accompanying the Provisional Specification, which are diagrammatic in nature, illustrate embodiments of the invention. In the drawings Figure 1 is a side elevation of a tamperproof cap according to the invention; Figure 2 is a section, on an enlarged scale, taken on the line II-II of Figure 1; and Figure 3 is a section similar to that of Figure 2, showing a different system of bridge weakening.

Figure 1 shows what is, for the most part, a conventional tamperproof cap, comprising an upper skirt portion 2, a lower security ring 3 and a weakened line formed by a series of alternate slits 4 and bridges 5.

In use, the cap shell is placed on a bottle, the upper skirt portion 2 is rolled or otherwise conformed to the shape of the bottle thread, and the lower part of the security ring 3 is tucked under an annular bead formed on the botlte neck. When it is required to open the bottle, the upper skirt portion 2 is unscrewed and the bridges 5 break. The upper part of the cap can then be removed, the security ring 3 remaining on the bottle.

In accordance with the present invention the bridges 5 are weakened along lines 6.

Weakened lines 6 extend the entire width of each bridge 5, between the upper corners of the two adjacent slits, or on a line parallel thereto and slightly below it.

The weakening line may be produced by cutting and compressing metal in the upper part of the bridges, as seen in Figure 2; or by moving the whole of the thickness of the bridge radially inwardly of the skirt of the cap as shown at 6 in Figure 3. In the Figure 3 construction, the metal bridge is suitably offset by a distance at least equal to 25%, and preferably at least 50%, of the thickness of the skirt. The precise amount of offset will in any particular case be determined having regard to opening torque requirements related to metal thickness and temper.

In the embodiment illustrated the slits 4 are all of the same size as are the bridges 5. There have in the past been proposed many variations of the bridge/slit formation, including the provision of relatively weak (narrow) bridges, relatively strong (wide) bridges, divided bridges, bridges spaced apart by narrow gaps and so on.

The present invention, in which the bridges are weakened, is applicable to all these types of bridge/slit formations.

It is found that when a cap according to the invention, screw-threadedly applied to a container, is desired to be removed, unscrewing of the top of the cap causes the bridges to sever substantially along the weakened lines 6 whereby the traces of the bridges 5 remain attached to the security ring 3. The lower edge of the removed upper part of the cap thereby has a projection-free uniform surface.

A further advantage of the invention is that it allows the bridges to be somewhat wider than has been the norm hitherto, but yet to be broken with similar opening torques to those required to open conventional pilferproof closures. This is of particular benefit in the case of long-skirted pilferproof closures, i.e. those wherein the sealing band or security ring is of greater axial extent than the upper part of the skirt, wherein much care has to be taken not to break the bridges when applying the caps to containers. Wider bridges, weakened in accordance with the invention, have greater axial rigidity and thus do not have such a tendency to break during application to a container.

WHAT WE CLAIM IS: - 1. A closure of the kind described, wherein each bridge in the circumferential weakening line is weakened across its width substantially along a line joining the upper corners of the adjacent slits.

2. A closure as claimed in claim 1 wherein each bridge is weakened by cutting and compression of the metal forming the upper part of the bridge.

3. A closure as claimed in claim 1 wherein each bridge is weakened by deforming the upper part thereof radially inwardly relatively to the remainder of the skirt of the closure.

4. A closure as claimed in claim 3 wherein the upper part of the bridge is offset from the remainder of the skirt of the closure by a distance equal to at least 25% of the thickness of the said skirt.

5. A closure as claimed in any of claims 1 to 4 wherein the sealing band is of greater axial extent than the upper part of the skirt.

6. A closure, substantially as hereinbefore described with reference to the drawings accompanying the Provisional Specification.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. parallel thereto and slightly below it. The weakening line may be produced by cutting and compressing metal in the upper part of the bridges, as seen in Figure 2; or by moving the whole of the thickness of the bridge radially inwardly of the skirt of the cap as shown at 6 in Figure 3. In the Figure 3 construction, the metal bridge is suitably offset by a distance at least equal to 25%, and preferably at least 50%, of the thickness of the skirt. The precise amount of offset will in any particular case be determined having regard to opening torque requirements related to metal thickness and temper. In the embodiment illustrated the slits 4 are all of the same size as are the bridges 5. There have in the past been proposed many variations of the bridge/slit formation, including the provision of relatively weak (narrow) bridges, relatively strong (wide) bridges, divided bridges, bridges spaced apart by narrow gaps and so on. The present invention, in which the bridges are weakened, is applicable to all these types of bridge/slit formations. It is found that when a cap according to the invention, screw-threadedly applied to a container, is desired to be removed, unscrewing of the top of the cap causes the bridges to sever substantially along the weakened lines 6 whereby the traces of the bridges 5 remain attached to the security ring 3. The lower edge of the removed upper part of the cap thereby has a projection-free uniform surface. A further advantage of the invention is that it allows the bridges to be somewhat wider than has been the norm hitherto, but yet to be broken with similar opening torques to those required to open conventional pilferproof closures. This is of particular benefit in the case of long-skirted pilferproof closures, i.e. those wherein the sealing band or security ring is of greater axial extent than the upper part of the skirt, wherein much care has to be taken not to break the bridges when applying the caps to containers. Wider bridges, weakened in accordance with the invention, have greater axial rigidity and thus do not have such a tendency to break during application to a container. WHAT WE CLAIM IS: -

1. A closure of the kind described, wherein each bridge in the circumferential weakening line is weakened across its width substantially along a line joining the upper corners of the adjacent slits.

2. A closure as claimed in claim 1 wherein each bridge is weakened by cutting and compression of the metal forming the upper part of the bridge.

3. A closure as claimed in claim 1 wherein each bridge is weakened by deforming the upper part thereof radially inwardly relatively to the remainder of the skirt of the closure.

4. A closure as claimed in claim 3 wherein the upper part of the bridge is offset from the remainder of the skirt of the closure by a distance equal to at least 25% of the thickness of the said skirt.

5. A closure as claimed in any of claims 1 to 4 wherein the sealing band is of greater axial extent than the upper part of the skirt.

6. A closure, substantially as hereinbefore described with reference to the drawings accompanying the Provisional Specification.