Bottles and jars – Closures – Frangible member or portion
Reexamination Certificate
1999-07-19
2001-01-16
Cronin, Stephen K. (Department: 3727)
Bottles and jars
Closures
Frangible member or portion
C215S318000, C215S320000, C215S354000
Reexamination Certificate
active
06173853
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a new and improved container closure and container neck structure and more particularly to a structure wherein the closure is applied with a single one-dimensional axial downward force onto the neck and is held in such position by a tamper-evident band. The consumer destroys a frangible connection between the cap and the band during initial removal, preferably by tearing away the band enabling the closure to be unscrewed from the container neck. When the cap is used for reclosure purposes, it may be screwed on and screwed off in the same manner as screw caps have heretofore been used.
2. Description of Related Art
Prior snap-on, screw-off structures may be classified under either of the following categories:
(1) Those with thread engagement as initially applied,
(2) Those without.
The major advantages of the no-thread initial engagement systems are that they are conceptually simple, careful alignment of the closure and the container is not necessary upon application of the closure, and easy (low force) application is possible since no thread-jumping is required. This version can be an aesthetically pleasing, straight wall of threads. On the other hand, the disadvantages of such a system are that it may be confusing to the consumer because initial removal is merely by lifting the cap off the neck but subsequent use requires twisting the cap relative to the neck. Further, it is difficult to use the system with a lined closure because of the height relationships between the finish and the cap, and finally the cap must be relatively tall, which forces the use of fine threads, which can be difficult to mold. None of these disadvantages are present in this invention.
A closure such as Cresci U.S. Pat. No. 4,561,553 has a number of problems. The tamper evident feature of the closure may be circumvented by being able to engage the threads of the neck and closure (thereby creating a mechanical advantage) and back off the cap while the tamper-evident band is intact. Secondly, the device is confusing to the consumer since the cap is screwed off during removal only by inwardly distorting the cap skirt. The cap is reapplied as a standard snap cap. thread engagement as the cap is initially applied has a number of conceptual advantages. Consumer confusion is eliminated since initial removal is by unscrewing. A number of seal systems, including foil, full liner, plugs or other linerless seals can be used. However, full engagement systems heretofore have been difficult to achieve in practice. A disadvantage of a closure such as Carr U.S. Pat. No. 4,625,875 is that there is no practical, consistent means to orient the cap relative to the container so that, after application, the cap must be turned at least slightly to ensure a tight seal. This defeats the purpose of a push-on cap. Also, the use of a stretch snap-band tamper evident ring excessively increases the application force necessary to seat the cap.
The present invention provides full thread engagement by reason of unique thread design and, more particularly, a unique tamper-evident band (i.e., lower skirt portion) attached to the upper part of the cap by multiple bridges or by means of a continuous line of weakness between the cap and tear band, as well as a means of orienting closure and bottle threads to achieve registration prior to straight axial application.
The present invention has considerable advantages over prior structures for the reasons above noted, among others.
SUMMARY OF THE INVENTION
The present invention comprises an improved closure or cap and an improved neck finish. The cap skirt and neck are provided with mating threads of such shape that the cap may be applied in a simple downward vertical movement, the cap skirt and neck flexing sufficiently to permit the threads to slip past each other.
The threads may be continuous or interrupted. Also, instead of there being two threads—one on the neck and one on the cap, one external thread may be replaced with a groove. The term “helical engagement means” is sometimes used herein to encompass all such screw retention means.
The cap has a tamper-evident tear band below the skirt which is connected to the skirt by a plurality of bridges or by a continuous line of weakness. Ratchet teeth are positioned on the inside of the tamper evident band. Correspondingly, the container neck below the threads is formed with external ratchet teeth. The mating ratchet teeth of the cap and container neck are engaged by the initial downward movement of the cap relative to the neck. In other words, in order to engage the ratchet teeth it is not necessary to rotate the cap relative to the neck, thereby differing from conventional threaded tamper-evident caps. It is merely necessary to provide alignment means on the cap and on the container so that the cap is initially properly oriented in such position that a direct single vertically downward movement of the cap relative to the neck causes the threads to slip relative to each other and the ratchet teeth to lock in final position. Chamfers on the ratchet structure of either closure or container can be used as a “fine” orientation system as the closure is initially applied.
To achieve proper registration of threads when a simple direct axial application force is used, both the neck threads and closure threads must be oriented. Orientation of the container is relatively easy. Generally, containers are either non-circular or have non-circular features which may be used for proper orientation. In accordance with a preferred form of the invention shown herein, the closure has a downward projecting tab similar to the tear tab used on push-on tear-off closures. The vertical tear tab characteristic of the present closure is an excellent orientation feature. However, other means for orienting the cap and container may be used.
Thread design is another feature of the invention. A large number of threads per inch of axial height is desirable for two reasons. First, a fine thread may be used and such a thread does not have to be as deep as a coarse thread, and hence the forces required for threads to jump during application are minimized. Secondly, fine threads minimize the height required to achieve a standard design criterion of 360° or more of thread engagement which permits a lighter closure weight.
The greater the number of thread leads, the less actual turning action is required to remove or reapply the cap. In addition, multiple thread leads promote more “squareness” during straight axial application. In other words, the cap seats horizontally on the neck because the termini of the threads are statically balanced. However, additional leads require a higher thread pitch assuming constant threads per inch and excessively high thread pitch results in a situation where the closure may back off or unscrew itself from sealed position.
In accordance with the present invention, a preferred thread for a blow-molded, high density polyethylene bottle is 12 threads per inch and two leads. If bottle finish processing permits, it would be advantageous to design for higher threads per inch and more leads. For example, if the bottle is made with injection blow mold equipment, a very fine bottle thread is possible. In that case, it might be preferable to use, for example, a 16 thread-per-inch, 4 lead, 4 pitch thread. The more leads, the more squarely the cap sets on the neck and the more effectively the closure will be seated by a direct downward, axial application force. Also, consumer advantages of quick release and reapplication can be achieved with multiple lead threads.
In order to provide a tamper-evident feature, the closure should not be removable without some apparent closure characteristic changing. Generally, this requirement is satisfied by incorporating a frangible section which is destroyed during initial closure removal. One type of frangible section is a continuous thinned tear line, but in a cap of the present invention, such a system may not be the best choice, although p
Cronin Stephen K.
Flehr Hohbach Test Albritton & Herbert LLP
Portola Packaging, Inc.
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