Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
PAIL CLOSURE
FIELD OF THE INVENTION
The present invention is directed to a combination
of a plug and an overlying threaded cap that in
combination form a closure on a lid of a plastic pail
lid. In particular aspects of the invention, the pail is
a pail intended for the packaging, storage and
transportation of paint.
BACKGROUND OF THE INVENTION
Plastic pails are used in a variety of end-uses, and
in an variety of sizes. One particular end-use is in the
packaging of paint. With the particular exception of
large industrial usage of paint where it is economical or
necessary to manufacture paint in large volumes or where
the colours, hues and tints must be very consistent from
batch to batch, paint is normally manufactured, stored
and shipped in a neutral color e.g. white, which is then
tinted just prior to use to form the particular shade of
paint required by the end-user.
Plastic pail are used for storage and shipment of
paint in volumes up to about 5 US gallons or 20 litres,
depending on the country, although larger pails may be
used. Lids for plastic pails intended for such use are
known to have closures incorporated into the lid,
especially to facilitate tinting of the paint and for
subsequent dispensing from the pail. The closure is
opened at the time that the selected color is being
prepared, and a tint concentrate added through the
opening in the lid. Subsequently, the lid is closed and
the pail containing the paint and tint are placed on a
shaker or roller for a period of time to effect thorough
mixing of the tint into the paint.
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For a closure to be acceptable, it must be easily
removed from the lid and then resealable after addition
of the tint to the paint. In addition, the closure must
be capable of withstanding the forces generated during
the shaking or rolling of the paint pail to effect the
mixing of the paint. The closure must prevent leakage or
spillage of the paint during such mixing or during
transportation, including by the customer. Moreover, the
closure should ensure that air does not enter into the
container and cause so-called "skinning" of the paint.
Two types of closure are known and generally used
within the industry. The first type of closure is a
removable and replaceable interference fit plug, which
may be pulled from the lid and then replaced to effect
closure. This type of closure may be referred to in the
paint industry as being a "tint cap". At the retail
store, the white base paint is often tinted. To do so,
the plug is pulled out by hand from the lid of the pail
to provide access to the contents of the pail, so that
colorant to be added to the white base paint. The plug
is then reinstalled by hand into the lid. The paint pail
is typically placed in a shaker or on a roller for mixing
of the paint. The agitation of the paint inside the
pail, especially on a shaker, creates considerable
pressure against the inside surface of the plug. If the
interference fit of the cap in the cover opening is
unable to withstand this force, the plug is dislodged,
and an unacceptable paint spill results. A more likely
occurrence is leakage of paint from the pail, around the
plug. This can also occur during transportation.
The second type of closure in common use is a
threaded cap. The threaded cap typically overlays a
removable but not resealable diaphragm which has been
integrally molded into the lid. The diaphragm, until
removed for tinting, provides additional protection
against paint spillage or skinning. To aid in its
removal, the diaphragm is supplied with a thin wall
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channel or parting line around its circumference. The
diaphragm can be fractured at the channel to effect
removal, by pulling with pliers on an integrally molded
tab, or by cutting with a knife. In use, the diaphragm
is broken away from the lid to enable the tint to be
added to the pail. Subsequently the threaded cap is
replaced on the lid without a diaphragm, both for mixing
on the shaker or roller and for subsequent
transportation. In practice, removal of the integrally
molded diaphragm has proven to be difficult. Operators
can cut themselves with knives, the diaphragm can spray
paint over the surrounding area and people as it is torn
out of the cover, or it can drop inside of the pail where
it cannot be retrieved. The diaphragm is not resealable
and is discarded. Once the tint has been added the
threaded cap is reinstalled, and the pail is placed on
the shaker for mixing. An leakage past the threaded cap
is unacceptable. Moreover, in transit threaded caps have
been known to vibrate loose which can lead to
unacceptable paint spillage or skinning.
SUMMARY OF THE INVENTION
A combination of plug and cap has now been found
that may be opened and resealed with a decreased
likelihood of leakage of paint during use.
Accordingly, an aspect of the present invention
provides a closure for a lid of a pail comprising:
a threaded neck extending from said lid, said neck
encompassing an annular orifice, said annular orifice
having an internal annular ring circumferentially located
therein;
a removable annular plug located within said
orifice, and being retained therein by an interference
fit with said annular ring;
a cap fitting on said threaded neck;
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said annular ring being cooperatively located such
that said cap contacts said plug and urges the plug into
interference fit with said annular ring.
In a preferred embodiment of the closure of the
present invention, the plug has a rim on its external
surface and the cap contacts said plug rim.
In another embodiment, the plug has an integral
handle on its external surface.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by the
embodiments shown in the drawings in which:
Fig.s lA and lB show schematic representations of a
removable interference fit plug of the prior art;
Fig.s. 2A and 2B show schematic representations of a
threaded cap overlaying an integrally molded removable
diaphragm of the prior art; and
Fig. 3 shows a schematic representation of an
exploded view of a pail closure of the invention; and
Fig. 4 shows a schematic representation of detail of
the threaded neck and annular ring.
DETAILED DESCRIPTION OF THE INVENTION
Fig. lA shows a plan view of a section of a lid,
generally indicated by 1, for a container, and represent
an embodiment of the prior art. Lid 1 has rim 2 that
extends around the periphery of the lid and encompasses
lid surface 3. Lid surface 3 has plug 4 therein, which
as noted above may be referred to in the trade as a tint
cap. Plug 4 has plug rim 5, which is an annular rim
extending around the periphery of plug 4. Plug surface 7
extends within plug rim 5 but is recessed downwards
therefrom. In the embodiment shown, plug 4 has pull tab
6 located on plug surface 7. Plug 4 fits into an annular
orifice which is not shown in Fig. lA.
Fig lB shows a cross-section of the plug shown in
Fig. lA. Lid 1 is shown as having a rim 2 from which
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extends lid surface 3. Plug 4 is located in lid surface
3, being in the orifice formed by lid surface orifice
edges 9. Plug body 8 extends through the orifice in lid
surface 3, being in contact with orifice edge 9. Plug
body 8 is shown as having plug lip 10, which is adapted
to be able to be pushed through the orifice in lid
surface 3, to enable plug body 8 to contact orifice edges
9, but be resistant to removal as a result of plug lip 10
engaging on orifice edge 9. Thus, an interference fit is
formed. Nonetheless, plug 4 is removable from lid
surface 3, using pull tab 6, as plug 4 is removed during
use to permit addition of tint to the pail. Plug rim 5
extends beyond the edges of orifice edge 9.
With respect to Fig. lA and lB, plug 4 is a
removable plug, by pulling on pull tab 6. Plug 4 is
removed from the lid, and the required tint composition
is added through the resultant orifice. Subsequently,
plug 4 is replaced and pushed in to give as tight a fit
as possible. The pail would then be subjected to shaking
to effect mixing of the tint with paint contained within
the pail.
Fig. 2A shows a plan view of another closure system
of the prior art, in which a threaded cap overlays an
integrally removable diaphragm. In Fig. 2A, lid 21 has
rim 22 and lid surface 23. Lid surface 23 has thereon a
threaded neck, which is not shown in Fig. 2A but may be
seen in Fig. 2B. The threaded neck has cap 24 thereon,
with cap edge 25 being screwed onto the threaded neck.
Cap surface 26 extends over the cap. Underlying cap
surface 26 is a diaphragm, of which diaphragm edge 27 and
diaphragm tab 28 are shown in Fig. 2A. Diaphragm edge 27
represents the parting line of the integrally molded
removable diaphragm, at which the diaphragm may be broken
away from the lid.
In Fig. 2B, there is shown a cross-section of the
lid of the prior art of Fig. 2A. Lid 21 has rim 22 from
which extends lid surface 23. Threaded neck 30 is
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located in lid surface 23 and extends upwards therefrom,
terminating at threaded neck edge 31. Within threaded
neck 30, and extending across the width of threaded neck
30, is diaphragm 29. Diaphragm 29 terminates near its
outer edges at diaphragm edge 27, which is the parting
line for the diaphragm from lid 21. Diaphragm 29 has
diaphragm tab 28 thereon. It will be noted that
diaphragm 29 is located in the lower portion of threaded
neck 30.
With regard to Fig. 2A and 2B, cap 24 is unscrewed
from lid 23 and diaphragm 29 is removed by pulling on
diaphragm 28. At that time, diaphragm 29 breaks away
from lid 21 at diaphragm edge 27. The tint is then added
through the resultant orifice and screw cap 24 is
replaced; it is understood that the diaphragm is removed
and is discarded, as it cannot be replaced into the
orifice under cap 24. Subsequently, the pail is
subjected to shaking to disperse the tint.
Fig. 3 shows a pail closure of the present
invention. A lid, generally indicated by 31, has rim 32
and lid surface 33 therebetween. Threaded neck 34
extends from lid surface 33, terminating in neck edge 35.
Located within threaded neck 34 is annular ring 36.
Annular ring 36 is spaced away from neck edge 35 but
closer thereto than the plane of lid surface 33.
Plug 37 is shown above threaded neck 34, in the
exploded view of Fig. 3. Plug 37 has plug body 38 which
extends downwards from plug top 39. The edge of plug
body 38 has plug ring 40. It is intended that plug body
38, and especially plug ring 40, will pass through
annular ring 36 of threaded neck 34 and form an
interference fit therewith.
The plug closure additionally has cap 41. Cap 41 is
intended to be screwed onto threaded neck 34. In doing
so, cap 41 contacts plug top 39, thereby forcing plug 37
downwards into contact with annular ring 36. Thus, plug
37 forms both an interference fit with annular ring 36
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and forms a pressure fit with cap 41, thereby forming a
double seal.
Fig. 4 shows threaded neck 34 extending from lid
surface 33, with annular ring 36 thereon, in greater
detail than in Fig. 3.
In use, the pail closure of Fig. 3 is removed from
lid 31, to allow tint to be added to the pail. This
involves unscrewing cap 31 and removing plug 37, at which
time the tint may be added through threaded neck 34 into
the pail. Subsequently, plug 37 is replaced in threaded
neck 34, and normally pushed into an interference fit
with annular ring 36. Screw cap 41 is then threaded onto
threaded neck 34 and tightened, at which time plug 37 is
forced into further contact with annular ring 36 and into
a pressure contact with cap 41.
The pail closure of the present invention provides a
double sealing system for containers of paint. In
particular, it provides both the tightened fit of plug 37
into lid 31 and the addition of cap 41, which
additionally forces plug 37 into further contact with
annular ring 36 to provide a better seal. Thus, each of
plug 37 and cap 41 provides seals, but cap 41 cooperates
by contacting plug 37, urging it into contact with the
annular ring to form the interference fit and prevent
plug 37 from becoming loose.
The closure may be used on a variety of pails, for
instance pails of up to and about 5 US gallon or 20 litre
capacity, although the closure is not restricted thereto.
