Tamper-proof closure cap with self-removing ring

A tamper-proof container closure cap is provided with a self-removing ring which breaks away from the cap in a strip as the cap is twisted open. Specifically, the cap is provided with a pawled ring which is split, frangibly attached to the cap adjacent each end, and free of engagement with the cap for a substantial distance in the direction opposing cap twist off. This structure effects removal of the ring from both the cap and the container as the cap is twisted off.

BACKGROUND OF THE INVENTION 
The present invention relates to tamper-proof container closures and, more 
particularly, to a tamper-proof container closure cap with a self-removing 
ring. 
Tamper-proof container closures are widely used, particularly in the dairy 
industry, to demonstrate to the final consumer that the contents of a 
container have not been contaminated or adulterated subsequent to 
bottling. One type of tamper-proof container closure employs a separable 
ring member having a plurality of triangular pawls to prevent such 
tampering. The ring is coupled to the cap by frangible elements located at 
discrete points around the cap. When the cap is twisted open, the pawls of 
the ring lock into engagement with corresponding teeth on the container, 
breaking the frangible elements, and separating the ring from the cap. 
Such closures are described in greater detail in U.S. Pat. No. 3,874,540 
issued to W. E. Hidding; U.S. Pat. No. 3,504,818 issued to H. Crisci et 
al.; and U.S. Pat. No. 3,249,247 issued to P. H. Babiol. 
One problem with these types of closures is proper disposition of the ring 
after separation. If the ring is secured to the container, it remains as 
an unsightly toothed structure permitting the collection of dirt and 
bacteria in tiny corners. If the ring is not secured to the container, it 
will either fall off during pouring from the container or it must be 
removed manually. Manual removal, which is usually effected after the cap 
is twisted off, almost inevitably results in unsanitary manual contact 
with the mouth of the container. 
In an attempt to overcome the problem of ring disposition, the industry has 
begun to provide the rings with handles so that they may be manually torn 
from the container and cap prior to removing the cap. Such handles, 
however are typically small molded structures readily subject to premature 
breakage. Moreover, the handles are typically secured to the ring by one 
or more frangible connections which must be manually broken before the 
handle can be pulled to tear the ring away. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a tamper-proof container closure 
cap is provided with a self-removing ring which breaks away from the cap 
in a strip as the cap is twisted open. Specifically, the cap is provided 
with a pawled ring which split, frangibly attached to the cap adjacent 
each end, and free of engagement with the cap for a substantial distance 
in the direction opposing cap twist off. This structure effects removal of 
the ring from both the cap and the container as the cap is twisted off.

DETAILED DESCRIPTION 
Referring to the drawings, FIGS. 1 and 2 are bottom and side views, 
respectively, of a typical closure in accordance with the invention. The 
closure 9 comprises a threaded cap 10 and a split ring 11 coupled to the 
cap by a plurality of frangible elements 12. The split ring 11 includes a 
plurality of triangular pawls 13 extending radially inwardly for 
interlocking with a plurality of teeth on a container (Elements 16 of FIG. 
3). Frangible elements 12 are disposed adjacent each end 14a and 14b of 
the split ring, but after the end element 14aa, the ring is free of 
engagement with the cap for a substantial distance in the direction 
opposing cap twist off, i.e., after the end element the next frangible 
element 12a is located so that the ring is free of additional frangible 
elements for an angular distance in excess of about 30.degree.. The 
closure is preferably molded of a flexible plastic material. 
The use and operation of this closure on a container is illustrated in FIG. 
3 which is an action perspective view in which the cap 10 of the closure 
is being twisted off a container 15. In preliminary operations, the 
container has been filled (contents not shown), and closure 9 has been 
twisted down onto a correspondingly threaded mouth 17 of the container. In 
the "twist on" direction, the pawls 13 of ring 11 have a gradual slope so 
that they slide over the teeth 16 of the container. In the "twist off" 
direction, however, the pawls have an abrupt slope and they interlock with 
the container teeth to prevent the ring from turning with the cap 10. As 
torque is applied to twist off the cap, the ring initially bend radially 
outward in the unengaged region subsequent to end 14a, and then the torque 
shears the frangible element adjacent 14a, permitting the ring to strip 
off both the cap 10 and the container 15. A similar sequence typically 
strips off the remainder of the ring as the cap is twisted off. However, 
in the event the ring does not completely strip off, the initial strip 
comprising the portion adjacent end 14a provides a ready means for manual 
removal of the remainder. 
In the preferred embodiment, which is made of high density polyethylene, 
pawls are distributed around the ring every 20.degree. of circumference 
except at end 14b. The frangible elements are all connected to pawls 
except, again, at end 14b where the element connects directly to the ring. 
The advantage of this structure is that the direct connection near end 14b 
does not readily break upon twist off, leaving a dangling strip to 
indicate tampering. 
While the invention has been described in connection with a specific 
embodiment, it is to be understood that this embodiment is merely 
illustrative of many other specific embodiments which can also utilize the 
principles of the invention. Thus, numerous and varied devices can be made 
by those skilled in the art without departing from the spirit and scope of 
the present invention.