Note: Descriptions are shown in the official language in which they were submitted.
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A REMOVABLE LID
The present Invention relates to a removable lid of the type that may be
applied to and
removed from a foodstuff container by a twisting action, and where the
container is
5 packed such that a negative pressure exists within the container with
respect to the
external pressure. More particularly, this invention relates to a removable
lid that is
easier to remove from the container.
Twist-off removable lids are often used with containers in order to provide a
hermetic
10 seal for holding foodstuffs such as cooking sauces, preserves and the
like. Typically
such lids are formed of a metallic body, usually steel, with a circular top
surface and
skirt portion. Threads or lugs are incorporated into the inside of lid to
compliment a
corresponding helical thread on the outside of the top of the container to be
closed.
During production the container may be "vacuum sealed" so improve the seal
between
15 the lid and the body. The lid may then be removed by a consumer by
twisting the lid to
unscrew it from the container. A flexible "vacuum button" may be formed in the
lid to
provide an indication that the vacuum is present.
Conventional twist-off removable lids have a reputation for being difficult to
open for
20 consumers. The reason for this is that in order to'remove the lid, the
consumer must
apply significant grip and torque to overcome the frictional force between the
lid and
the container which is accentuated by the axial load provided by the vacuum
inside the
container. This can prove troublesome for some people, particularly those who
are
elderly, young or suffer from a physical disability or impairment such as
arthritis.
In an attempt to address this, consumers have come up with a large number of
methods to more easily remove twist-off lids, including tapping the corner of
the lid
against a hard surface, striking the corner of the lid with a knife or running
hot water
over the lid before twisting. These methods are not always successful and can
be
30 dangerous if the container is made of glass. In addition to these
methods, numerous
utensils have been manufactured with the specific intention of aiding in
opening twist-
off lids. However, most of these utensils work by simply increasing the
consumer's grip
on the lid, and do not reduce the amount of torque required to overcome the
frictional
force.
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US3410436 describes a closure cap that is provided with a vent means. The vent
means can be opened at a weakened portion by finger pressure. However, this
creates a sharp edge on which users may cut themselves. Furthermore, it has
been
found that, when making closure caps in accordance with this document, it is
not
5 possible to achieve a deep enough score at the weakened portion to allow
it to be
broken by finger pressure alone. Any attempt to mechanically score to the
required
depth causes the material to rupture spontaneously.
WO 2010/151165 discloses a vacuum tight single part closure, which comprises a
10 conical centre part with a line of weak resistance scored around its
perimeter on an arc
of 90 ¨ 270 degrees. The purpose of the score line is so that when the central
cone is
depressed, the score line will be broken, breaking the seal on the container
and
equalising the pressure allowing the closure to be removed. The figures show
the
housing for the rubber gasket being raised compared to the level of the score
fine.
It is an object of the present invention to overcome or at least mitigate the
difficulties
experienced by the consumer when removing lids from food-storage containers as
described above. This object is achieved by providing an improved removable
lid that
enables consumers to first release the vacuum within the container before
attempting
20 to remove the lid.
According to a first embodiment of the present invention there is provided a
removable
lid for use with a food-storage container, the lid having a user-actuable
vacuum-release
button comprising: at a first level, a raised surface for contact with a
user's finger; at a
25 second level, lower than the first level, a curved score line adjacent
to said raised
surface; and at a third level, being intermediate between said first and
second levels, a
surface adjacent to said curved score line on the other side from said raised
surface,
The surface at the third level is positioned to prevent the user's finger from
coming into
contact with the curved score line during actuation of the button.
A range of curved profiles have been tested and it was found that one curved
generally
around the finger actuation point gives the lowest opening force for a given
score
residual and is therefore the easiest to open closure with minimal chance of
accidental
opening.
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Embodiments of the present invention provide an easy-to-use, integrated
solution that,
when in use, allows consumers to more easily remove lids from containers,
without the
need for separate utensils or for carrying out potentially unsafe methods.
5 The curved score line may be such that the user-actuable vacuum-release
button can
be actuated to fracture along the score line by finger pressure. The length of
curved
score line may be less than 2cm.
The lid may further comprise a centrally located pop-up button to indicate
whether or
10 not a vacuum is present, and said curved score line is located radially
outward of the
button.
The surface of the lid proximate to the curved score line may be decorated and
contain
an embossed pattern, which may comprise ridges formed in the material of the
lid.
15 Also, the surface of the lid within the curved score line may be raised
to form a button. -
The force required to actuate the vacuum-release button may be between 10N and
40N, and it may be 20N. Too small a force may lead to accidental opening in
transit or
capping and too great a force will make the button difficult to open.
The lid may further comprise one or more formations or lugs for engaging screw
threads on the food-storage container.
The curved score line may be formed by laser scoring, or by mechanical
scoring, and
25 the depth of the curved score line may extend between 50% and 100%
through the
thickness of the lid.
The thickness of the lid may be substantially 0.16mm, and the curved score
line may
cut the thickness to,substantially 0.02mm.
The material of the lid at the point of the score line may be reduced to a
depth of less
than 50 microns, and it may be reduced to a depth of around 20 microns
The depth of the curved score line may extend 100% through the thickness of
the lid.
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A sealing compound may be provided on the underside of the removable lid
underneath the user-actuable vacuum-release button. The sealing compound may
peel away from part of the lid during actuation of the vacuum-release button
to expose
an opening.
The removable lid may be substantially metal, for example it may be
substantially steel.
According to a second embodiment of the invention there is provided a product
comprising a food-storage container and a removable lid as described in any of
the
previous statements.
The interior of the container may be at a negative pressure with respect to
the
atmosphere such that the removable lid is removably sealed to the food-storage
container by a pressure differential.
According to a further embodiment of the present invention there is provided a
removable lid for use with a food-storage container, the lid having a user-
actuable
vacuum-release button provided by a curved score line.
For a better understanding of the present invention and in order to show how
the same
may be carried into effect reference will now be made, by way of example, to
the
accompanying drawings in which:
Figure 1 shows a perspective view of a removable lid;
Figure 2 shows an enlarged cross-sectional detail of the score line in the
removable lid
of Figure 1;
Figure 3 shows a perspective view of the removable lid of Figure 1 attached to
a
container;
Figure 4 shows a perspective view of another removable lid;
Figure 5 shows an enlarged cross-sectional detail of the removable lid of
Figure 4;
3D Figures 6a and 6b show a perspective view of a further
removable lid from above and
below respectively;
Figure 7 shows an enlarged cross-sectional detail of the user-actuated vacuum-
release
button of the removable lid of Figures 6a and b; and
Figures 8a and 8b show enlarged cross-sectional details of the user-actuated
vacuum-
release button of Figure 7 before and after a force is applied;
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Figure 9 shows an enlarged cross section of a user-actuable vacuum release
button
according to an embodiment of the invention..
As discussed above, conventional removable lids can be difficult to remove
from
5 foodstuff containers due to the need to overcome the frictional force
between the lid
and container which is accentuated by the vacuum inside the container.
A removable lid will now be described with reference to the figures that can
overcome
this difficulty by allowing the consumer to first easily release the vacuum
within the
10 container before attempting to twist off the lid. This is facilitated by
providing a
weakened score line on the top surface of the lid. The score line is generally
curved,
e.g. arcuate, in shape to match the shape of a finger tip, and can take the
form of an
arc segment. Figure 1 shows a perspective view from above of a removable lid 1
comprising a top surface 2 that is circular in shape, and a "skirt" 3 that
extends down
15 from the edges of the top surface 2. The top surface 2 and the skirt 3
together form an
interior recess underneath the lid, and the inside walls of the skirt 3
comprise a helical
thread that engages with a corresponding helical thread on a container.
Alternatively,
instead of a full helical thread being formed into the lid, there may be a
number of
formations or lugs that engage with helical threads on the container.
The lid 2 is intended to be used with vacuum-sealed foodstuff containers, for
example
glass mason jars used to contain cooking sauces, preserves or similar. The lid
will
typically be made of steel. During the production process in which the
foodstuff is
introduced into the jar, the lid hermetically seals the jar with a negative
pressure
25 ("vacuum") inside to strengthen the seal and possibly aid in the
preservation of the
food. The top surface 2 comprises a "pop-up" button 4 formed as part of the
top
surface. If there is a vacuum inside the jar then the pop-up button 4 remains
depressed. If there is no longer a vacuum in the jar, then the pop-up button
will be
released and the consumer can press it down to feel and hear a "click" or
"pop" which
30 acts as an indication to the consumer that the jar has been opened.
Figure 1 also shows a curved score 5 on the top surface 2 of the lid. This
score
provides a weakened line in the steel of the lid that can be broken when a
force is
applied to it. The score is made in the top surface during manufacture of the
lid, and is
35 made off-centre such that it doesn't overlap with the pop-up button 4.
In this way,
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pressing the pop-up button 4 will not fracture the curved score line 5. There
are
numerous ways in which the score can be formed, examples of which are laser
= scoring, machining, or mechanical scoring (e.g. using a press and anvil).
By fracturing
the top surface of the lid at the curved score line, air is allowed to enter
the jar through
5 the newly made opening, therefore releasing the vacuum inside.
Also shown formed on the top surface in Figure 1 is an embossment pattern that
comprises ridges formed into the top surface of the lid. This embossment
pattern acts
as an indicator to the consumer where best to place a finger in order to apply
pressure
10 to the score line and fracture it.
Figure 2 shows an enlarged section of the top surface 2 containing the score
line 5 in
cross-section, taken perpendicular to the score line. Typically the thickness
of the
steel, as indicated by the distance a, is around 0.16mm. At the score line 5,
the
15 thickness of the steel, indicated by the distance 13, will be reduced to
about 0.02mm.
However, a can be a thickness in the range 0.10 to 0.3mm, and 13 can be
between
0.005 and 0.1mm.
Figure 3 shows the lid 1 as shown in Figure 1 attached to a jar 10. Arrows A
to C
20 indicate the events that take place when a consumer first opens the jar.
Initially the jar
is unopened, therefore the vacuum within is intact and the pop-up button 4 has
not
been released. The consumer first applies a force A to the area indicated by
the
embossed pattern 6 in the top surface 2. This causes the top surface to
fracture at the
score line 5, and air enters the jar through the resulting opening. As a
result, the
25 vacuum within the jar is released, and the pop-up button 4 is released
as indicated by
arrow B. The release of the pop-up button 4 is often accompanied by a "pop" or
"click"
type sound which acts as an audible indication to the consumer that the vacuum
has
been released, Now the consumer can proceed with twisting off the lid 1 from
the top
of the jar 10 in the normal fashion, as indicated by arrow C. As there is no
longer a
30 vacuum seal to overcome at the twisting off stage, the force required is
significantly
reduced.
An alternative removable lid is shown in Figure 4. Instead of the embossed
pattern of
the removable lid of figure 1, a raised button 12 is provided adjacent to the
score line 5,
35 and the shape of the button compliments the shape of the score line,
i.e. the score line
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extends partially around the button. The raised button may be formed from
extra
material added to the top surface. However, the embodiment shown is formed by
shaping the steel top surface to incorporate the raised button at the desired
location.
Figure 5 shows a cross section of the lid of Figure 4 along the dotted line D.
The score line can, in a further alternative, reduce the thickness of the lid
down to
Omm, i.e. the score line breaks through the lid. Figures 6a and 6b show the
top and
underneath respectively of such a lid. From the top, the lid looks the same as
the
previous removable lids. There is a generally arcuate score line 5, with a
raised button
12 formed in the top surface 2, along with a pop-up button 4. Underneath,
however,
there is an area of compound 14 underneath the button and score line. This
compound
14 seals the lid, maintaining the vacuum and protecting the cut edge provided
by the
score line 5. Figure 7 shows a cross section through the score line 5 and
raised button
- 12, and includes the compound 14 on the underside of the
top surface. This
compound can be made from a plastic, foil patch, hot melt or rubber-type
material.
Figures 8a and 8b show how the seal provided by the compound 14 is peeled away
from the top surface when a force F is applied to the top of the raised
button, and an
opening 15 is created through which air can enter the container to release the
vacuum.
The resulting opening that is formed in the top surface when the score line is
fractured
may be sharp and so, to avoid consumers injuring themselves, there is provided
a
removable lid wherein the area of the top surface that contains the score line
is slightly
lower compared to the rest of the top surface. An example of this is shown in
Figure 9.
Figure 9 shows a section of the lid in cross-section at the point of the user-
actuable
button. A higher lever surface 20 is provided at a first level A. This higher
level surface
acts as an indicator for the user, showing where to apply finger pressure. The
score
line 5 is provided in a lower level surface 21 that is adjacent to the higher
level surface
20 at a second level B that is lower than level A. An intermediate level
surface 22 is
provided at a third level C that is between levels A and B. The intermediate
level
surface 22 is adjacent to the lower level surface 21, on the other side from
the higher
level surface 20. During actuation of the button, the user applies pressure to
the higher
level surface 20 causing the lid to fracture along the score line 5. The
position of the
score line within the lower level 21, between the higher and intermediate
level surfaces
20 and 22, prevents the user from coming into contact with the sharp edges of
the
fractured score line.
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The resulting opening does not need to be large as it only requires that air
is able to
enter the jar to equalise the pressure difference, and so the part of the top
surface that
is displaced by the force applied by the consumer does not need to be
displaced by
5 very much. Typically the maximum displacement will be less than 1mm, and
once the
force is removed the resilience of the material will return that part of the
top surface
substantially to its previous position. Thus the consumer will not see a hole
in the
closure after opening.
10 It has been found, through testing, that score lines with a groove with
a depth of less
than 50 microns are successful in being openable by finger pressure. This
level of
scoring is not easily achievable by conventional scoring methods. Therefore,
the
preferred method of creating the score line is to machine the material by
laser to a
depth of less than 50 microns, and preferably to 20 microns. Of course, other
methods
15 of creating the score line can be used.
It will be appreciated by the person of skill in the art that various
modifications may be
made to the above described embodiments without departing from the scope of
the
present invention.
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