Note: Descriptions are shown in the official language in which they were submitted.
~l~9~L-13
This invention relates to containers and closures
therefor and is concerned particularly with the seating of
closures upon container rims and the sealing effect pro-
vided between closures and the rims.
In closure and container constructions in which
effective sealing between the two components is of utmost
importance, separate annular seals may be provided, these
seals either being detachable from the closure or container
or being secured in position by adhesive. To attain a
positive seal and positive seat between conventional con-
tainers and their closures while preventing movement of the
closures upon the containers, it is necessary fully to com-
press the seals by the closure force between the two com-
ponents. However, after the full closure force has been
applied for a period of time, mechanical hysteresis takes
effect and a seal tends to become set in its compressed state
thereby reducing the resilient reactive force applied against
~:. the container so that the sealing effect is at least partial-
ly destroyed. Further, altough a seal may be sealing
efficiently, it may have set at least partly towards its
compressed state in which it is faithfully shaped compli-
mentarily to any imperfections against a container or closure
, seat. In such a case, once the closure has been removed,
because it may never be possible for it to be replaced in
exactly the same circumferential position upon its container,
leakage may take place. Also, when such containers and
. closures are filled with stored material and are stacked on
~ top of each other, the weight upon the lower containers is
!s . such as to increase compression of the seals. In this event,
once the weight has been removed from the lower containers,
-- 2 --
.~ ~
19
there is an increased likelihood of leakage around the
seals of these containers because any relaxation of pressure
of a closure upon its container may not necessarily be
accompanied by a relaxation of the seals.
It may be thought possible that containers and
closures could be designed in such a way that the compress-
ive force applied to seals is reduced thereby reducing the
possibility of the seals becoming set once they have been
compressed so as to resist any tendency for there to be a
leakage path developing around the seals. However, it is
difficult to design constructions in which seals are sub-
jected to large degrees of compression without resulting in
an assembly in which there is less positive attachment of
closures to containers and resultant sloppiness of fit
which is not a desirable characteristic of containers,
especially those of large capacity.
A container and closure assembly, according to
the invention, comprising a closure provided with a container
closure portion surrounded by an annular rim portion, includ-
ing a downwardly depending annular flange. The container
has a sidewall terminating at its upper end in a rim. The
closure is closed upon the container rim and the rim and rim
portion have mutually engaged locking means retaining the
closure upon the rim. The rim and rim portion axially
compress, between them, a resilient seal. The resiliency of
the seal determines the normal relative closed positions of
the closure and container. The closure is movable under
downward external pressure from the normal closed position
further in the closing direction relative to the container,
so as to increase axial compression upon the seal. The
closure and container mutually comprising an axially facing
surface and a surface opposing the axially facing surface.
419
,'
The axially facing surface has a plurality of circumferent-
ially spaced-apart ribs projecting axially therefrom and
towards the opposing surface. The ribs are spaced from the
opposing surface in the normal closed position of the con-
tainer and closure. Movement of the closure in the closingdirection causes the ribs and the opposing surface to
engage one another to terminate the movement, with gaps
being formed between the axially facing and opposing surfaces
at positions between the ribs into which a prizing tool may
s, 10 be inserted for removing the closure from the container.
The invention contemplates a preferred structure
, in which the container has an outwardly radial shoulder
with an upper surface and the ribs extend upwardly from the
i shoulder. Movement of the closure in the closing direction
,js 15 causes the ribs to be engaged by the opposing surface pro-
vided by the closure. The gaps are formed between the
shoulder and the closure. In another preferred aspect,
the container has an annular reinforcement of open-sided
box construction, extending radially outwards from the
sidewall and the ribs extend upwardly from the reinforce-
ment. Movement of the closure, in the closing direction,
`
causes the ribs to be engaged by the opposing surface pro-
vided by the closure. The gaps are formed between the
annular reinforcement and the closure.
In another preferred aspect, the reinforcement
comprises two annular spaced-apart flanges extending
radially from the sidewall and a plurality of axially
extending walls which join the flanges together and which
are spaced apart circumferentially of the sidewall. The
ribs extend upwardly from the uppermost annular flange.
Each rib may be located directly above an axially extending
wall.
-3a-
11~9~19
It is envisaged that the distance between the rib
and the other surface may be possibly up to .020 inches but
it is preferred that the distance should be no greater than
.010 inches.
Embodiments of the invention will now be described
. by way of example with reference to the accompanying drawings
in which:-
;1 FIGURE 1 is a side elevational view of a container
and closure assembly according to a first
embodiment;
FIGURE 2 is a cross-sectional view along the axis
of the assembly showing part of the
assembly on a larger scale than that shown
in Figure l;
FIGURE 3 is an isometric view of part of the
container shown in Figure 2;
FIGURE 4 is a side elvational view of a container
and closure assembly according to a
second embodiment;
FIGURE 5 is an isometric view of part of the con-
tainer of Figure 4 but on a larger scale;
and
;
~9~
FIGURE 6 is a cross-sectional view along the axis
of the assembly and showing part of the
assembly.
As shown in Figure 1, in a first embodiment a
2-gallon container and closure assembly generally shown by
numeral 1 includes a container 2 and closure 3 both moulded
from high density polyethylene although other suitable
mouldable plastics materials, e.g. polypropylene, may be
used. The closure 3 comprises a container cover portion 4
which is surrounded by an annular rim portion 5. The rim
portion 5 is of inverted U^shape having an annular inner
wall 6 spaced around which is an outer annular wall 7, the
two walls being joined together at their base 8. Lying
within the U-shaped rim at the base is a resilient O-ring
seal 9 made of elastomeric material. The outer wall 7
extends downwardly and part way down its length is provided
with a locking means in the form of a radially inwards pro-
jection 10. Below the projection 10, the outer wall 7 is
splayed outwards slightly at 11 and terminates in a planar
annular foot or flange 12. The flange 12 has a lower planar
axially facing surface 13.
The container 2 has a side wall 14 which is of
frusto-conical form and having at its wider upper end a rim
15 which is approximately 9 inches in diameter and has a
locking means in the form of a downwardly depending shoulder
16 which is engaged by the projection 10 to hold the con-
tainer and closure assembled together. The seal 9 is
trapped between the rim 15 of the container and the base 8
of the U-shaped rim portion of the closure and the resilient
nature of the seal normally holds the container and closure
11~19~
together with the shoulder 16 engaged by the pro;ection 10
as shown in Figure 2. There is, therefore, no means provided
~s for positive engagement of the closure and con~ainer togethers in their closing direction upon assembly so that if a loaded
container of similar construction is placed on top of the
assembly in stacking relationship during storage, this
immediately means that the seal 9 will be compressed further
as the closure is moved downwards onto the container so as
~ to disengage the projection from the shoulder 16. To prevent
; 10 the over-engagement of closure and container going beyond
specified and desirable limits such that undue distortion of
the seal 9 would take place, a means is provided for prevent-
ing over-engagement of the closure and container. This
means which comprises the lower surface 13 of the flange 12
also includes a plurality of radially extending circum-
ferentially spaced-apart ribs 17 which extend outwards from
and are spaced from the side wall of the container. The
, ribs which are spaced about 2 inches apart also extend up-
wardly from an upwardly axially facing surface of an annular
shoulder 18 which projects outwardly from the side wall.
Each rib is of rectangular cross-section and tapers upwardly
to a horizontal surface 19 which is about 1/2" wide and
opposes the surface 13 of the flange 12 while being spaced
slightly below it in the normal position of the closure and
container, i.e. when the shoulder 16 is engaged by the pro-
jection 10. In this condition of the parts of the assembly,
the distance between the surfaces 13 and 19 is preferably of
the order of between .008 and .010 inches.
In use of the above construction, when the con-
tainer is filled with a product and the closure is placed on
-- 6 --
~ 4 1 ~
top, the resilient seal 9 effectively seals between the parts
while holding the projection lO in engagement with the
shoulder 16. Should the container be placed in a stack of
stored containers with a container or containers located on
top of the closure 3, then a force is applied to the closure
which has the effect of resiliently loading the seal 9 so as
to force the closure further downwards onto the container,
i.e. in the closing direction. Clearly, such force would
have the effect of compressing the seal 9 possibly to its
limits without the use of the annular flange 12 and the ribs
17. However, after the closure has moved by up to 0.10
inches in the example, the surface 13 engages the surfaces
19 of the ribs so as to prevent any further downward move-
ment of the closure and the weight of the stack of containers
above the assembly is carried through the closure and down
the container side wall.
It is clear, therefore, from the above that the
seal 9 even under loaded conditions is not distorted to any
substantial extent beyond its normal closed position as
shown in Figure 2. This means that should the assembly be
removed from the stack, then the seal should not have set
unduly in position and will still seal effectively between
the container rim and the base of the U-shaped rim portion
of the closure.
In contrast to this, in a situation in which no
opposing movement limiting surfaces are provided, i.e. a
construction not coming within the scope of the invention,
it could be found that the seal 9 would be compressed to
such an extent that after a period of time in loading con-
dition the elastomeric material had become set so that when
'119
;
the closure and container return to their relative normal
position, a gap or gaps would develop around the seal thus
allowing for contamination or leakage of the contained
product.
Apart from the fact that the above described
construction allows for a sealing action to take place
which is permanent even after the assembly has been removed
i from a loaded stack of containers, the assembly is also
constructed so as to enable the closure to be removed from
the container fairly simply. While minimum gap requirements
are provided between the surfaces 13 and 19, the use of the
shoulder 18 spaced from the surface 13 provides a gap
between spaced-apart ribs into which a prising tool such as
- a screwdriver or opening bar may be inserted.
In a second embodiment having all the advantages
` discussed above for the first embodiment, a 5-gallon con-
- tainer and closure assembly as shown in Figure 4 comprises a
container 20 and closure 21.
As is shown by Figures 5 and 6, the container 20
has ribs 17 which serve to prevent the closure from moving
downwardly beyond a limit determined by the engagement of an
axially facing undersurface 22 of the closure with the ribs
when similar and filled containers are in a stacked condition.
As described for the first embodiment, therefore, this pre-
vents undue compression of a compressible O-ring seal 23
which lies between the base of a U-shaped rim 24 of the
closure and a rim 25 of the container.
For the purpose of preventing undue distortion of
the side wall 26 of the container under the load imposed
upon it by stacked containers above it, a side wall reinforce-
~ 4 ~ 9
ment 27 carries the ribs 17. This reinforcement also ensures
the loads upon the container are dissipated into the side
wall without the build-up of any undue stress conditions
which could lead to splitting of the plastic material forming
the side wall. The reinforcement comprises two annular
planar flanges 28 and 29 which extend radially outwards from
the side wall 26 in slightly spaced apart relationship and
these two flanges are integrally joined together, not only
by the side wall itself, but also by a plurality of cir-
cumferentially spaced, radially and axially extending walls
30 which make the reinforcement into a box construction
which is open-sided, i.e. is open in the radial direction.
The upper flange 28 is integrally formed with the upstanding
ribs 17 extending from an axially facing upper surface of
the flange. The ribs are preferably positioned directly
above the walls 30 as shown in Fîgure 5. The relative
dimensions and relative positioning of the walls 30 and
flanges 28 and 29 are subject to design considerations and
are not considered to be limitations necessary to the box
section reinforcement. In the 5-gallon container being
described the walls 30 lie about 1" apart around the con-
tainer and the flanges 28 and 29 are approximately 1/2 inch
apart with the thickness of walls and flanges being about
.090 inches.
In use of the 5-gallon container and closure
assembly when it is stacked in filled condition with other
containers above it, the seal 23 is compressed until the
closure undersurface engages the rîbs 17. Thereafter, sub-
stantially no further compression of the seal 23 takes place
and the stacking load is taken through the ribs 17 and into
~ 9
the side wall 26 through the reinforcement 27. If the
stacking load is particularly excessive, the reinforcement
27, because of its box construction, resists any tendency
to twist upon the side wall so that virtually no distortion
of the side wall takes place and side wall splitting or
cracking is avoided.
It will, of course, be realized that ribs may be
provided upon the closure instead of upon the container.
In a practical construction, i.e. a modi~ication of the
second embodiment (not shown), ribs 17 would be omitted from
the flange 28 and ribs would extend downwardly from the
undersurface 22 of the closure with which they would be
integral. In the modification, the closure ribs would
normally be spaced from the flange 28 but would engage the
flange during downward movement of the closure 90 as to
prevent overengagement of container and closure.
:~,
- 10 -
