EP0698559A2

EP0698559A2 - Tamper-evident closure and tamper-evident closure and container combination

Info

Publication number: EP0698559A2
Application number: EP95305360A
Authority: EP
Inventors: Gerald L. Roy
Original assignee: Kerr Group Inc
Current assignee: Kerr Group Inc
Priority date: 1994-08-24
Filing date: 1995-07-31
Publication date: 1996-02-28
Also published as: AU1491695A; EP0698559A3; MX9502429A; CA2144910A1

Abstract

A tamper-evident closure (2) includes a threaded closure and tamper-indicating features. The features have upwardly and inwardly folded tabs (121) which lock against the lower surface of an annular shoulder (202) on a container neck (203) to retain the tamper-indicating features on the neck as the closure is removed. The tamper-indicating features include a pilfer ring (125) to which the tabs are integrally connected. The tabs are resilient and are flexed by the container finish at the joints where they are joined to the pilfer ring. The closure of the present invention may be installed simply by screwing it onto a container neck in a one-step process. The flexible tabs assist in guiding the closure and centering it when installed onto the container neck and do not require the holding of the closure or the container finish to close tolerances in order to be consistently effective. A thin web (123) of material is provided between the tabs which prevents the outward bending of the tabs which may occur during shipping or handling. The invention also provides the tamper-evident closure and container combination.

Description

The present invention relates to a tamper-evident closure with a thin web of material formed between the tamper-evident tabs. The invention also relates to a tamper-evident closure and container combination.
Tamper-evident closures of various types have been used in the past on containers to enable the user of a product to determine whether the container has been opened. Such closures have commonly been made of aluminum or plastic.
One type of closure includes an upper cap portion and a lower security ring or band which is attached to the cap portion by a failure line. When the cap is removed. the closure breaks along the failure line, leaving the ring separate from the cap portion. Often the security ring is heated and rolled under a shoulder of the container: plastic closures of this type are described in U.S. Patent Nos. 3,673,761 and 4,033,472.
U.S. Patent Nos. 4,506,795 and 4,595,110 describe tamper-evident closures with tamper-indicating tabs which fold upwardly and inwardly and lock against the lower surface of an annular shoulder on a container neck to retain the tamper indicating means on the neck as the cap is removed. The tamper indicating means has a ring to which the tabs are integrally connected at their lower outer ends. The tabs are resilient and are flexed by the container finish at the joints where they are joined to the ring. These closures may be installed simply by screwing them onto a container neck in a one step process. The flexible tabs guide the closure and center it as it is lowered onto the container neck for installation. They do not require the holding of the closure or the container finish to close tolerances. However. there is a small chance in such a system that flexible tabs may turn outwardly during shipment.
There is a need for an improved tamper evident closure which may be simply installed on a container finish and yet will not suffer the drawbacks of inadvertent outwardly flexing tabs.
These and other needs are met by the tamper-evident closure and the tamper-evident closure and container combination of the present invention. A tamper-evident closure is provided for sealing an open-topped container. A container of the present invention has an external screw thread formed on the neck of the container and an outwardly projecting annular shoulder formed below the screw thread on the container. A closure of the present invention has an internally threaded closure which may be removed from the container for dispensing the contents of the container. The closure has a base wall for extending across the open top of the container, an annular sidewall integrally joined to the base wall about the periphery of the base wall and depending from it, and tamper-indicating features. The tamper-indicating features include a pilfer ring depending from the annular sidewall and located axially in vertical alignment with the sidewall, a number of flexible tabs connected to the pilfer ring capable of being bent upward and radially inward from the pilfer ring for contacting the annular shoulder of the container during removal of the closure to prevent the pilfer ring and tamper-indicating features from traveling upward beyond the annular shoulder with the rest of the closure. As such the pilfer ring then breaks away from the closure. The tamper indicating features also include webbed areas located between the flexible tabs to prevent the flexible tabs from flexing outwardly.
The closure may be advantageously made of plastic.
The tabs in the present invention join the pilfer ring along folded joints, and the tabs are spaced from each other in a circumferential direction. The cross-sectional thickness of the tabs may be substantially equal to the cross-sectional thickness of the pilfer ring portion to which they are joined. The tabs are preferably substantially rectangular in shape and project upwardly and inwardly. The webbed areas are also substantially rectangular in shape, however, the cross-sectional thickness of the webbed areas is substantially less than the cross-sectional thickness of the tabs.
By way of example, the invention will be further described with reference to the accompanying drawings in which:-

FIG 1 shows a side view of an embodiment of a closure of the present invention with webbing between the tabs;
FIG 2 shows a side view of an embodiment of a container of the present invention with an annular shoulder ;
FIG 3 shows a side view of an embodiment of a closure of the present invention, with the tabs in a flexed position just prior to installation on a container neck ; and
FIG 4 shows a side view of an embodiment of a closure of the prior art, with the tabs in an undesired "tab-out" condition.

FIG 1 illustrates an embodiment of a closure 2 of the present invention. Closure 2 has a base wall 112. Depending from the periphery of the base wall 112 is an annular sidewall 110. The interior of the annular sidewall 110 has threads for engaging corresponding threads on a container neck. The annular sidewall 110 is frangibly connected to a pilfer ring 125 through a weakened area 124.
Depending from the pilfer ring 125 are a series of tabs 121a, 121b, 121c...., 121n. In this application, if an individual tab is mentioned, the term "tab(s) 121k" will be used. However, if characteristics of all of the tabs are discussed the general term "tabs 121" will be utilized. The tabs 121 are spaced circumferentially from each other. Between the tabs are placed webs 123a, 123b, 123c...., 123n, which tend to tie the movement of one tab 123k to the movement of its neighboring tabs 123(k-1) and 123(k+1). These webbed portions are preferably rectangular in shape so as to well-match the space between the tabs. The webs 123 generally do not extend as far, in a downward direction, as do the tabs 121. The thickness of the material from which the webs 123 are constructed is also preferably less than that of the tabs 121, so as to allow a reasonable amount of flexibility.
FIG 2 shows an embodiment of a container 200 of the present invention has a shoulder 204 from which a neck 203 extends upwardly. The neck 203 has opening 205 through which the contents of the container 200 may be dispensed. The exterior of neck 203 has threads 201 which threadingly engage corresponding threads on the interior of the annular sidewall. Finally, the neck 203 has an annular shoulder 202 which provides a projection which tabs 121 may push against so as to hold the pilfer ring 125 below the annular shoulder.
When the closure 2 is used to seal the open mouth of the container 200. the closure 2 is installed by being screw-threaded onto the neck 203 of the container 200.
Prior to the capping operation, the tabs 121 must be flexed inward so that they extend radially and inwardly, pointing towards the interior of the ciosure 2. as shown in FIG 3. Once the tabs 121 are flexed inwardly, the closure 2 may be placed onto the container 200. During this installation procedure, the tabs 121, so flexed, contact the threads 201 but travel over them. The tabs 121 also travel over the annular shoulder 202. Once past these obstructions, the tabs 121 flex slightly inwardly toward the central axis of the closure 2.
This flexing of the tabs 121 inhibits upward motion of the closure 2 because the tabs 121 engage the annular shoulder 202 but may not pass back over the shoulder 202. Thus, the tabs 121 hold the pilfer ring 125 onto the container neck 203, which in turn holds the closure 2 onto the container neck 203 via the weakened area 124.
When a user wishes to dispense some or all of the contents of the container 200, the user rotates the closure 2 off of the container 200. This rotational motion is, of course, translated into an upward force by the action of the threads. As the closure 2 is forced upward, tension is exerted on the weakened area 124 because the upward motion of the closure 2 is countered by the downward force of the tabs 121 against the annular shoulder 202. That is, the tabs 121 keep the pilfer ring 125 at or below the level of the annular shoulder 202, while the user's rotation of the closure 2 forces the closure 2 upward.
After more rotation of the closure 2, and its subsequent upward motion, enough tension is placed on the weakened area 124 that it ruptures and breaks. This frangible quality of the weakened area 124 thus allows the closure 2 to be removed from the container neck 203 while leaving in place, under the annular shoulder 202, the pilfer ring 125 and tabs 121. The presence of the pilfer ring 125 and tabs 121, separated from the closure 2, thus alerts the user that the closure's seal has been broken and that at least one person has gained entry to the closure prior to its use by the user.
The presence of the tabs 121 also assist in the initial installation of the closure 2 onto the container 200. This is because the inwardly flexed tabs 121 tend to guide the closure 2 onto the container neck 203 during installation, even if the alignment of the closure 2 and the container neck 203 is not exact. In particular, if the alignment is not exact, the tabs 121 tend to push the closure 2 and or container 200 into alignment.
FIG 4 demonstrates the situation where no webs are between the tabs. Wall 412 has depending skirt 410. Tabs 421a, 421b, etc. surround the base. It is clear that, in both the initial installation and the operation of the tabs to produce a tamper-evident feature, that the tamper-evident result is defeated if one or more tabs inadvertently flex outward at any time prior to installation, as is shown in FIG 4. Such a "tab-out" condition may occur during shipment or during the installation itself. As may be seen from FIG 4, the tab-out condition is exacerbated by the independence of movement of individual tabs 421k. In other words. because the movement of one tab 421k is not connected in any way to the movement of another, once a tab 421(k-1) has flexed outward, its neighboring tabs 421(k-2) and 121k do not influence its movement. In particular, the neighboring tabs do not serve to pull the tab 121(k-1) back in line.
FIG 3 shows that, in addition to the inventive features discussed above, the present invention also includes webs 123 placed between the tabs 121. The webs 123 are advantageously present just near the base of the tabs 121, in particular, at the folded joints where the tabs 121 connect with the pilfer ring 125. However, the webs 123 may extend even as far as the tabs 121 themselves. Generally, the webs are made of a similar material as the closure, but their thickness is generally less so as to not inhibit the tabs' inward movement. These webs prevent the outward flexing of the tabs 121 by connecting the movement of one tab 121k with the movement of its neighboring tabs 121(k-1) and 121(k+1). In this way, the webs 123 serve to keep the tabs 121 from flexing outward by providing tension against outward movements in which the average distance between points on adjacent tabs 121 becomes relatively large. The webs 123 do not, however, prevent the tabs 121 from flexing inward because the inward flex tends to decrease the distance between the tabs 121. That is, the webs 123 are useful for preventing the tab-out condition, but do not inhibit the effectiveness of the tabs 121 in providing a tamper-evident feature.
The weakened area 124 may include, for example, a circumferential cut in a series of frangible connecting posts (not shown) which hold the pilfer ring 125 to the rest of the closure 2. The circumferential cut is made in the pilfer ring (or above the pilfer ring), which cut can be such that few of the connecting posts remain, or most of the connecting posts survive the cutting, as desired. As the present invention includes a pilfer ring 125 with tabs 121 and webs 123, the volume of the closure 2 below the weakened area 124 is relatively heavy. As such, the frangible connecting posts, in this example, may need to be manufactured in an especially strong manner to ensure that the pilfer ring does not break away during installation. It has been found that a preferable width and thickness of such a connecting post lies in the range of .010 to .025 in. The preferred materials are polyolefins such as polystyrene or polypropylene.
From the foregoing, it will be appreciated that an improved tamper-evident closure is provided by the present invention. While a certain embodiment of the present invention has been shown and described herein, there is no intent to limit the invention by this description. The invention extends to all modifications and alternate constructions falling within the spirit and scope of the appended claims.

Claims

A tamper-evident internally threaded closure for sealing a container having an external screw thread formed on a neck of the container and an outwardly projecting annular shoulder formed below the screw thread on the container, the closure comprising:
a base wall;
an annular sidewall integrally joined to the base wall about the periphery of the base wall and depending therefrom;
a pilfer ring frangibly depending from the annular sidewall, said pilfer ring being located axially in vertical alignment with said sidewall;
a plurality of flexible tabs connected to the pilfer ring capable of being bent upward and radially inwardly from the pilfer ring for engaging the annular shoulder of the container during removal of the closure to prevent the pilfer ring from traveling upward beyond the annular shoulder with the closure and to break the pilfer ring away from the closure; and
a plurality of webbed areas located between the flexible tabs to prevent the flexible tabs from flexing outwardly.
The closure of claim 1, wherein the closure is made of plastic
The closure of claim 1 or claim 2, wherein folded joints join the tabs to the pilfer ring, the tabs being spaced from each other in a circumferential direction.
The closure of any one of the preceding claims, wherein the tabs have a cross-sectional thickness substantially equal to the cross-sectional thickness of the pilfer ring portion to which they are joined.
The closure of any one of the preceding claims, wherein the tabs are substantially rectangular in shape and project upwardly and inwardly.
The closure of any one of the preceding claims, wherein the webbed areas are substantially rectangular in shape.
The closure of any one of the preceding claims, wherein the cross-sectional thickness of the webbed areas is substantially less than the cross-sectional thickness of the tabs.
The closure of any one of the preceding claims, further comprising a plurality of connecting posts frangibly connecting the pilfer ring with the annular sidewall.
The closure of any one of the preceding claims, wherein said pilfer ring and said annular sidewall are separated by a circumferential cut, such that said cut defines a weakened area.
A tamper-evident closure and container combination, comprising:
an open-topped container having an external thread formed on a neck on the container and an outwardly projecting annular shoulder formed below the screw thread on the container;
an internally threaded closure according to any one of the preceding claims.
The combination of the claim 10, wherein the closure and container are made of plastic.
The combination of claim 10, wherein said container is made of glass.