Container and closure

A lid has an inverted U-shaped peripheral rim, which rim snaps over the upper edge of a container sidewall. There are three separate sealing zones between the lid and the container. First, the cover portion interior of the snap on rim has a plug fit interference relationship with the interior of the container. Second, the outer leg of the snap on rim has an interference relationship with an outwardly extending sidewall ridge near the upper edge of the container. Third, the outer leg of the snap on rim also has an inwardly facing ridge which snaps over the sidewall ridge and has an interference relationship with the outer surface of the container sidewall. A tear-off strip constitutes the lower portion of the outer leg of the snap on ridge and tears off below the inwardly facing ridge. The lower edge of this tear off strip abuts against a ledge which extends outward from the container sidewall thereby inhibiting tampering with the strip until initial opening is intended. A vertical weakening line adjacent a pull tab on the tear-off strip further inhibits tampering with the tear-off strip.

BACKGROUND OF THE INVENTION 
This invention relates in general to reusable containers having tight 
fitting covers and to such containers as are adapted to include a tear-off 
strip to provide security in that the strip must be removed the first time 
the container is opened. 
There are many container designs intended to serve this reusable function. 
U.S. Pat. No. 3,753,511 issued on Apr. 21, 1973 to Heinz Ruch discloses a 
snap-on closure having an inverted U-shaped rim which fits over the rim of 
the container sidewall to permit resealing of the container after it has 
been initially opened. This Ruch patent also teaches the use of a tear-off 
strip at the bottom of the outer leg of the inverted U-shaped rim of the 
closure. The user can readily determine that the container has initially 
been opened because the tear-off strip has been either removed or 
obviously tampered with. 
One of the important purposes of this invention is to provide an improved 
closure or cover in that, when reclosed, the cover will provide an 
effective seal to keep the contents of the container from being affected 
by the ambient atmosphere. 
It is a related purpose of this invention to provide this seal with a 
closure that can be manually snapped on and which will then be held on 
against any tendency to pop open because of air pressure within the 
container. 
It is a further related purpose of this invention to provide such a closure 
in a design that can incorporate a tear-off strip which will indicate 
whether or not the container has been initially opened and thus will 
provide a degree of assurance against premature tampering with the 
contents of the container. 
It is a related purpose of this invention to provide a design which 
minimizes the risk that the purpose of the tear-off strip can be 
compromised and thus will minimize the ability of an individual to remove 
the closure without detaching the tear-off strip. 
BRIEF DESCRIPTION 
Briefly, one embodiment of this invention is a plastic container with a 
circular sidewall. The closure that covers the top of the container has an 
inverted U-shaped rim that fits over the rim of the container sidewall. 
The inner leg of the inverted U-shaped rim has an interference fit with the 
container sidewall so that the plastic cover has a plug fit relationship 
with the open top of the container. Thus when closure is made, a first 
sealing zone is provided between the contents of the container and the 
ambient atmosphere. 
At the rim of the container sidewall there is an outwardly extending 
circumferential ridge which has an interference fit relationship with the 
outer leg of the inverted U-shaped rim portion of the closure. This 
provides a second sealing zone and resists any tendency of the closure to 
be popped off by air under pressure in the container. 
In addition, there is an inwardly extending circumferential ridge on the 
outer leg of the inverted U-shaped closure rim which is positioned to snap 
over and underlie the outwardly extending ridge on the container sidewall 
when closure is made. This provides a snap on closure and an interference 
relationship between the two ridges that further tends to hold the closure 
on the container against air pressure in the container. Further, this 
inwardly extending ridge has an interference fit relationship with the 
outer surface of the container sidewall and thus provides a third sealing 
zone and further resists any tendency of the closure to pop off. 
The container sidewall has an outwardly extending circumferential ledge 
spaced below the outwardly extending ridge. A circumferential tear-off 
strip constitutes the lower portion of the outer leg of the inverted 
U-shaped closure rim. In the closed state, the bottom edge of this 
tear-off strip abuts against the ledge thereby making it difficult to 
remove the cover without first removing the tear-off strip. A tab on the 
tear-off strip permits ready removal of the strip. A weakened vertical 
line adjacent the tab causes an initial break in the tear-off strip if 
someone attempts to use the tab to push off the cover without first 
removing the tear-off strip.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
All of the FIGS. show the same embodiment. 
The plastic container 10 is essentially cylindrical although, in one 
embodiment, sidewall 12 flares outwardly slightly at a 1.degree. angle 
with the vertical, so that the diameter at the bottom of the container is 
slightly less than the diameter at the top of the container. This 
facilitates stacking the container on top of one another. The base wall 14 
is slightly concave to provide improved container stability. The base 14 
is preferably joined to the sidewall 12 with a large radius in order to 
optimize container strength. 
As may best be seen in FIG. 3, a circumferential outwardly extending ridge 
16 is positioned close to the upper edge of the sidewall 12. Spaced below 
this ridge is a circumferential outwardly extending ledge 18 having a 
horizontal upwardly facing ledge surface 18s. As can better be understood 
after a description of the cover 12, this sidewall ridge 16 provides an 
engaging surface and an interference frictional fit with the cover to aid 
in keeping the cover in the closed state when closure is made. The ledge 
18 provides increased assurance that the contents of the container cannot 
be reached without breaking or removing the tear-off strip. 
The cover 20 has a recessed center area 22 which provides closure across 
the mouth of the container 10. A circumferential inverted U-shaped rim 24 
around this center area provides the desired sealing and security. This 
rim 24 has a circumferential inner leg 26 and a circumferential outer leg 
28. 
The inner leg 26 extends up from the center area 22 so that when closure is 
made, the center area 22 is recessed below the upper edge of the container 
sidewall 12. The outer diameter of this inner leg 26 is a few thousands of 
an inch greater than the inner diameter of the container sidewall near the 
upper edge of the sidewall. Thus there is a slight interference fit 
between the inner leg 26 and the sidewall 12. This provides a plug fit 
between the closure 20 and the container 10 to effect a first sealing of 
the contents of the container from the atmosphere when the container and 
closure are in the closed state shown in FIG. 5. 
The outer leg 28 of this inverted U-shaped sealing rim 24, includes an 
inwardly projecting circumferential ridge 30. When closure is effected, 
this ridge 30 rides over and under the sidewall ridge 16 thereby providing 
a snap on closure. In the closed state, the ridge 28 underlies the ridge 
16 and thereby provides interference between ridges 16 and 30 that resists 
opening of the cover. The material out of which both the container 10 and 
the cover 20 are made is a resilient plastic material so that the outer 
leg 28 will flex sufficiently to permit removing the cover 20 and 
reclosing the cover 20. 
The outer diameter of the sidewall ridge 16 is slightly greater than the 
inner diameter of the outer leg 28 in the zone above the ridge 30. Thus, 
in the closed state, there is an interference fit between outer leg 28 and 
ridge 16 to effect a second sealing zone that not only protects the 
contents of the container from communication with the atmosphere but also 
provides additional gripping power to resist having the cover 20 pop off 
spontaneously under the pressure of air within the container 10. This is 
particularly important when one considers that the closure is a plug type 
of closure that tends to cause some compression of the air within the 
container after full sealing is affected during closure. In one embodiment 
this interference fit between outer leg 28 and ridge 16 is in the range of 
ten thousands of an inch (0.010 inches). 
Further sealing and further resistence to having the cover spontaneously 
pop off is provided by having an interference fit between the ridge 30 on 
the outer leg and the sidewall 12 of the container. In particular, in one 
embodiment, the inner diameter of the ridge 30 is about 8 mils (0.008 
inches) less than the outer diameter of the adjacent container wall 12. 
It has been found that the combination of the interference fit between 
inner leg 26 and sidewall 12, together with the inteference fit between 
ridge 16 and outer leg 28, in further combination with the interference 
fit between ridge 30 and container wall 12 provides a particularly 
effective seal and provides a high degree of assurance that once closure 
is effected, closure and sealing will be maintained throughout a wide 
range of conditions to which the container may be subjected. 
The lower portion of the outer leg 28 constitutes the tear-off strip 32. A 
circumferential notch 33 below the ridge 30 and along the inner surface of 
the leg 28 provides a weakening line that permits ready removal of the 
tear-off strip 32 when initially opening the container. A projecting tab 
34 is attached to the tear-off strip 32 so that the strip 32 can be 
readily removed. 
The length of the outer leg 28 to the bottom edge of the tear-off strip 32 
is such as to result in the bottom edge of the tear-off strip 32 abutting 
the ledge surface 18s when the cover 20 is closed. It thus becomes very 
difficult to remove the cover 20 without first removing the tear-off strip 
38. To prevent compromising the closure by having someone attempt to push 
the cover up through the tab 34 without removing the tear-off strip, a 
further notch 36 provides a vertical weakening line through the tear-off 
strip 32 which will break on manipulation of the tab 34. 
In one embodiment where the container 20 has an open mouth of approximately 
5 inches in diameter and a height of nearly six inches, the following 
dimensions are held in order to provide the various interference 
relationships disclosed above. 
The plug fit is attained with an inner leg 26 that has an outer diameter of 
4.996 inches. The inner diameter of the container wall 12 at its upper 
edge is 5.006 inches. But at a distance of 0.35 inches down from the upper 
edge, the inner diameter of the container sidewall 12 is 4.994 inches. 
Since the inner leg 26 extends down the inner surface of the sidewall 12 
by close to 3/8 of an inch, there is an interference fit relationship of 
about 1 mil (0.001 inches) on a radius and about two mils on a diameter 
over a length of close to 20 mils of the inner leg 26. 
With respect to the interference relationship between the ridge 16 and the 
outer leg 28, the inner diameter of the outer leg 28 in the area above the 
ridge 30 is 5.134 inches while the outer diameter of the ridge 16 at its 
greatest extension is 5.144 inches. Thus over a short distance, there is 
an interference fit relationship of approximately 5 mils on a radius and 
10 mils on a diameter. 
With respect to the interference relationship between ridge 30 and the 
container sidewall 12, the inner diameter of the ridge 30 is 5.094 inches 
while the outer diameter of the container is at that height from the 
ground is 5.102 inches. Thus there is an interference relationship of 4 
mils on a radius and 8 mils on a diameter. 
An embodiment of the invention has been disclosed in which the container 
has an essentially circular sidewall. It should be understood that the 
invention could be applied to other shaped containers and in particular to 
a container having a rectangular type of cross section with four 
sidewalls. It should be understood herein, therefore, that the term 
circumferential refers to the entire circumference of whatever shape 
container embodies the invention. 
By virtue of the above design, a container and reusable enclosure is 
provided which is initially substantially tamper proof and once opened can 
be reclosed a number of times while providing an effective seal to prevent 
communication between the interior of the container and the ambient 
atmosphere and to resist tendencies for the closure to pop off when, for 
example, the atmosphere in the container exerts pressure tending to cause 
spontaneous opening of the closure.