U.S. patent application number 15/315749 was filed with the patent office on 2017-04-13 for lid structure for container.
This patent application is currently assigned to N.V. Nutricia. The applicant listed for this patent is N.V. Nutricia. Invention is credited to Franck Perek.
Application Number | 20170101229 15/315749 |
Document ID | / |
Family ID | 50979853 |
Filed Date | 2017-04-13 |
United States Patent
Application |
20170101229 |
Kind Code |
A1 |
Perek; Franck |
April 13, 2017 |
LID STRUCTURE FOR CONTAINER
Abstract
A lid is disclosed for a container having a peripheral wall
extending to an upper edge and defining a product containing space.
The lid structure comprises a lower frame, an upper frame and a
lid. The lower frame connects to the upper edge of the tub and
defines an access opening giving access to the product containing
space. The upper frame is connectable to the lower frame in a
snap-fit connection and forms a circumferential first seal
therewith. The lid is arranged to close the opening, the lid and
the upper frame forming a circumferential second seal. In this
manner, an improved sealing connection can be achieved and the
upper frame can be manufactured separately from the lower frame and
joined thereto at a later stage of the production process.
Inventors: |
Perek; Franck; (Utrecht,
NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
N.V. Nutricia |
Zoetermeer |
|
NL |
|
|
Assignee: |
N.V. Nutricia
Zoetermeer
NL
|
Family ID: |
50979853 |
Appl. No.: |
15/315749 |
Filed: |
June 5, 2015 |
PCT Filed: |
June 5, 2015 |
PCT NO: |
PCT/NL2015/050408 |
371 Date: |
December 2, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65D 51/247 20130101;
B65D 2543/00296 20130101; B65D 21/0209 20130101; B65D 2543/0012
20130101; B65D 51/20 20130101; B65D 43/163 20130101; B65D
2543/00435 20130101; B65D 43/02 20130101; B65D 2543/00231
20130101 |
International
Class: |
B65D 43/16 20060101
B65D043/16; B65D 21/02 20060101 B65D021/02; B65D 51/24 20060101
B65D051/24; B65D 43/02 20060101 B65D043/02; B65D 51/20 20060101
B65D051/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2014 |
NL |
PCT/NL2014/050359 |
Claims
1. A lid structure for a container having a peripheral wall
extending to an upper edge and defining a product containing space,
the lid structure comprising: a lower frame for connection to the
upper edge of the container, the lower frame defining an access
opening giving access to the product containing space; an upper
frame, connectable to the lower frame in a snap-fit connection and
to form a circumferential first seal therewith; and a lid, arranged
to close the opening, the lid and the upper frame engaging to form
a circumferential second seal.
2. The lid structure according to claim 1, wherein the snap-fit
connection is located radially inwardly of the first seal.
3. The lid structure according to claim 1, wherein the snap fit
connection comprises a plurality of downwardly extending barbs on
the upper frame, which engage through detent openings in the lower
frame.
4. The lid structure according to claim 1, wherein the first seal
comprises an upstanding first rim on the lower frame, which engages
within a downward extending first groove of the upper frame.
5. The lid structure according to claim 1, wherein the second seal
comprises an upstanding second rim on the upper frame, which
engages within a downward extending second groove of the lid.
6. The lid structure according to claim 4, wherein the first and/or
second grooves are circumferential and are provided with lead-in
structures that extend radially on both sides of the respective
grooves by a distance at least equal to a width of the respective
first and second rims.
7. The lid structure according to claim 1, wherein the upper frame
has an external circumferential skirt and the lid has an exterior
surface, the exterior surface and skirt being co-planar in the
closed position of the lid.
8. The lid structure according to claim 1, wherein the upper frame
has an external circumferential skirt and the lower frame has a
peripheral surface, the peripheral surface and skirt being
co-planar when the upper frame and lower frame are connected
together.
9. The lid structure according to claim 1, wherein the lid is
pivotally connected to the upper frame.
10. The lid structure according to claim 9, wherein the lid is
arranged to pivot about a hinge located radially inwardly from an
external periphery of the upper frame.
11. The lid structure according to claim 9, wherein the second seal
commences engagement when the lid is at an angle of more than
15.degree. to the upper frame.
12. The lid structure according to claim 9, wherein the second seal
comprises an upstanding second rim on the upper frame, which
engages within a downward extending second groove of the lid having
a circumferential inner wall and a circumferential outer wall,
wherein the circumferential outer wall extends downwards a distance
greater than the circumferential inner wall in a region adjacent to
the hinge.
13. The lid structure according to claim 1, wherein the first and
second seals are insect-tight seals.
14. A package comprising: a container having a peripheral wall
extending to an upper edge and defining a product containing space;
and a lid structure, the lid structure comprising: a lower frame
connected to the upper edge of the container, the lower frame
defining an access opening giving access to the product containing
space; an upper frame, connectable to the lower frame in a snap-fit
connection; and a lid, arranged to close the opening.
15. The package according to claim 14, further comprising a
membrane seal for sealing the product containing space prior to
use.
16. The package according to claim 14, wherein the container is a
thin-walled thermoformed tub having a wall thickness of between 0.1
and 0.6 mm.
17. The package according to claim 14, consisting of a single
material class for the purposes of recycling.
18. The package according to claim 14, wherein the container
further comprises a carton sleeve enveloping and supporting a thin
walled, thermoformed tub.
19. The package according to claim 14, wherein the lower frame is
permanently connected to the upper edge of the container.
20. The package according to claim 14, further comprising a
quantity of powdered infant milk formula sealed within the product
containing space.
21. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] The present invention relates to containers for the
packaging and dispensing of products, in particular powdered
products such as infant nutrition or milk formula. The invention
relates in particular to a lid structure for such a container
having a re-closable lid.
[0003] Description of the Related Art
[0004] Powdered material, such as infant milk formula, has been
sold in various forms of package for many years. Metal cans were
initially the preferred container as they were relatively easy and
cheap to produce and could be sealed for long term storage. The
seal comprised an aluminium foil across the mouth of the container
that was removed on first use. As a single container would be used
for an extended period, the containers were provided with
re-closable plastic lids which gripped over the outer rim of the
metal can. A measuring scoop was frequently included with the
container, either packaged separately or within the can itself.
Such cans are however relatively heavy and expensive to
produce.
[0005] More recently, alternative packaging forms have become
available which improve on the existing cans. These include
laminate container bodies and plastic hinged lid and rim
structures, which may be glued to the container body. One such
package is described in U.S. 2008041861, having a seal for
initially closing the package and a space between the seal and an
upper edge of the container for partially receiving the scoop prior
to use. The container part may consist of a laminate of carton,
metal foil and plastic material. A further similar package is shown
in WO2010071424.
[0006] Sealing of such packages after initial opening is a major
issue in the design of a lid structure. Packages to be used with
infant formula or other comestibles should be sealed sufficiently
to prevent ingress of mites or similar creatures. A maximum opening
of 70 microns has been considered desirable. In other situations,
still better sealing may be required in order to prevent ingress of
moisture. The conflicting requirements of a large opening for easy
scoop access with a cost effective construction are difficult to
reconcile. In particular, for a disposable package, the volume of
material that can economically be used in the lid construction
limits its strength. A relatively deformable lid is also more
difficult to effectively seal against a rim that also deforms.
Existing structures, such as that shown in U.S. 2008041861, use lid
and rim structures, sometimes referred to as toptainers, that
connect to the free upstanding edge of the container body. This
connection is also critical in the sealing of the container.
Another design shown in WO2008083141 uses an additional integral
gasket to assist sealing.
[0007] A container for holding paint or other liquids is described
in U.S. Pat. No. 5,975,346A. The container includes a body having a
bottom wall and a side wall extending from the bottom wall along
the periphery of the bottom wall which terminates in an upper rim.
The container also includes an annular retaining ring secured to
the upper rim and a lid pivotally and detachably mounted to the
annular retaining ring for movement between an open position and
closed position.
[0008] In the light of these design requirements and constraints,
it would be desirable to improve on the existing designs.
BRIEF SUMMARY OF THE INVENTION
[0009] According to the invention, there is provided a lid
structure for a container having a peripheral wall extending to an
upper edge and defining a product containing space, the lid
structure comprising: a lower frame for connection to the upper
edge of the tub, the lower frame defining an access opening giving
access to the product containing space; an upper frame, connectable
to the lower frame in a snap-fit connection and forming a
circumferential first seal therewith; and a lid, arranged to close
the opening, the lid and the upper frame forming a circumferential
second seal. In this manner, an improved sealing connection can be
achieved and the upper frame can be manufactured separately from
the lower frame and joined thereto at a later stage of the
production process.
[0010] In a preferred embodiment of the invention, the snap-fit
connection is located radially inwardly of the first seal. This
effectively means that the snap-fit connection is at an inside of
the container with respect to the location of sealing. In the case
that the snap fit connection passes through the lower rim, its
location inwardly of the seal is of no detriment to the overall
sealing. This arrangement allows more convenient manufacturing
processes to be applied in e.g. an injection moulding
procedure.
[0011] Preferably, the snap-fit connection is a permanent
connection that cannot be released without otherwise damaging the
container. Alternatively, the snap-fit connection may be releasable
such that the upper frame and lid may be removed and e.g. used
again on another package. According to a further preferred
embodiment, the snap fit connection comprises a plurality of
downwardly extending barbs on the upper frame, which engage through
detent openings in the lower frame.
[0012] The first and second seals according to the invention are
preferably insect-tight seals. In the following, an insect-tight
seal will be defined as a seal that avoids any opening of 70
microns or greater at any point of the seal. Experience in the
field of food packaging in tropical climates has determined that
this value is generally adequate to avoid ingress of the smallest
insects that may be detrimental to food hygiene. By providing the
first and second seals to be insect-tight, ingress of such insects
to the interior of the container can be avoided, even after the
container has been first opened and when powder particles are
present around the lid and frames. The first and second seals may
also be water-tight, preferably to at least 3 cm of water.
[0013] Preferably, the first seal comprises an upstanding first rim
on the lower frame, which engages within a downward extending first
groove of the upper frame, preferably in an interference fit. The
first rim and first groove preferably continue uninterrupted around
the full circumference of the first seal. A seal of this type has
considerable advantage over a single sided seal. The rim and groove
can easily be formed to have an interference fit and the
insect-tightness described above can be readily achieved. For
features produced by injection moulding techniques, their accuracy
is dependent upon the dimension of the feature being formed. For a
groove having a dimension of less than 2 mm, a 3% manufacturing
tolerance can be accepted without compromising the seal. In the
case of a single sided seal, the critical size of the feature would
be the overall diameter of the opening, For an opening of 10 cm
diameter, the same tolerance would give a size variation of 3 mm,
making an interference fit difficult to guarantee.
[0014] Preferably, the second seal also comprises an upstanding
second rim on the upper frame, which engages within a downward
extending second groove of the lid, preferably in an interference
fit. The second rim and second groove preferably also continue
uninterrupted around the full circumference of the second seal.
This arrangement also benefits from the advantages of manufacture
as indicated above and can thus easily achieve the insect-tightness
required. As will be understood, the direction of the rims and the
grooves can be reversed without affecting the sealing function. It
is noted however that for use in this manner a downwardly extending
groove is less likely to collect debris.
[0015] Most preferably, the first and/or second grooves are
provided with lead-in structures that extend radially on both sides
of the respective grooves by a distance at least equal to a width
of the respective first and second rims. As has been indicated
above, manufacturing tolerances of injection moulded items must be
taken into account and although the variation in the interference
dimension may be slight, the positional variation of the groove
with respect to the rim may be significantly greater. The lead-in
structure is arranged to ensure that entry of the rim into the
groove is achieved easily and without damage to either.
[0016] The lid is intended to be opened and closed frequently
during use and, for this reason, the second seal must be robust
enough to withstand such use without damage, wear or otherwise
losing its insect-tightness. In one advantageous embodiment, the
lead-in structure on the second groove comprises lead-in flanges.
These may be arranged as perpendicular buttresses to the second
groove that reinforce the second groove against sideways
distortion. It will be understood that a defined position of the
second groove may be important during closing of the lid to ensure
correct entry of the second rim. Misalignment of these structures
may cause damage to either the second rim or the second groove,
making subsequent closure more difficult and impeding the
insect-tight seal. To achieve their support function, the lead-in
flanges may be present around the circumference of the second
groove, preferably on both sides thereof. They may be present at
intervals of less than 20 mm, preferably less than 15 mm and in the
corner regions may even be more closely spaced. By providing
support to the second groove, the walls of the second groove may be
made more flexible, thereby better accommodating the second rim. To
fulfil their lead-in function, the lead-in flanges may extend
downwards to beyond the lowest extent of the second groove and be
angled or curved smoothly towards this groove.
[0017] The first seal between the upper frame and the lower frame
is generally intended to be assembled once and thereafter not to
require resealing. Nevertheless, joining of these components may
take place in an automated procedure and subsequent to manufacture
and stress-relaxation of the respective components. For this
reason, the first groove may also be provided with similar lead-in
flanges at least at its outer periphery. This can assist in self
centering the upper frame and lower frame during assembly.
[0018] According to one embodiment of the invention, the upper
frame may have an external circumferential skirt and the lid may
have an exterior surface, with the exterior surface and skirt being
co-planar in the closed position of the lid. In this sense,
co-planar is not intended to be limited to flat planes and may also
include a curved plane. As a result of this shape, the lid and
upper frame may form a smooth transition without
discontinuities.
[0019] According to a further aspect of the invention, the upper
frame has an external circumferential skirt and the lower frame has
a peripheral surface, the peripheral surface and skirt being
co-planar when the upper frame and lower frame are connected
together. As above, this allows a smooth transition between the
upper frame and the lower frame.
[0020] The lid may be manufactured as a separate item to the upper
rim and may be removable therefrom. Preferably however, the lid is
pivotally connected to the upper frame. In one embodiment, the lid
may be arranged to pivot about a hinge that is located radially
inwardly from an external periphery of the upper frame. Prior
designs have used hinge structures that allow a lid to pivot with
respect to a rim at a position radially outwards from an external
periphery of the rim. Such a protruding hinge structure may
interfere with stacking and can be unsightly in the final
product.
[0021] As a result of the pivotal closure of the lid, correct
engagement of the second rim into the second groove is important if
easy closure without damage to the second seal is to occur. A
lead-in structure is important in achieving such closure. In order
to further improve the closing action, the downward extending
second groove of the lid may have a circumferential inner wall and
a circumferential outer wall, wherein the circumferential outer
wall extends downwards a distance greater than the circumferential
inner wall in a region adjacent to the hinge. The inner wall may
thus not be uniform in height around its full circumference and may
curve gradually downwards from either end of the container towards
the middle of the rear side of the container. The second rim may
also be devoid of lead-in flanges in this regions, which may extend
all along the hinge side of the lid. In the absence of lead-in
flanges, the inner and outer walls are better able to flex as the
second rim enters the second groove. On closing of the lid, this is
the portion of the second rim that first engages with the second
groove and it does so at a relatively large angle. In one
embodiment the circumferential second seal commences engagement
when the lid is at an angle of about 20.degree. to the upper frame.
Engagement of the second rim into the second groove continues
progressively as the lid closes. This gradual engagement of the
second seal and the frictional engagement between the inner wall
and the second rim provides the user with tactile feedback of the
sealing action, which is quite different from snap-fit type seals
which only provide feedback at the final point of snapping
engagement.
[0022] According to a further advantageous embodiment of the
invention, the upper frame may be formed of a material having a
different hardness to that of the lower frame or the lid. In one
embodiment, the upper frame is formed of a first plastic material
that is relatively softer than a second plastic material used for
the other two components. A relatively harder material for the
lower frame and lid can ensure a greater overall stiffness of the
lid structure. Alternatively, the upper frame may be slightly
harder. Alternatively, all three components may be of different
hardness. The variations in hardness may be slight and may be just
sufficient to ensure good interference sealing between the
respective seals. Preferred materials for the lid and upper and
lower frames are polypropylene (PP), polyethylene (PE) and
polyethylene terephthalate (PET) or combinations thereof, although
the skilled person will be familiar with various alternatives which
could provide similar engineering properties,
[0023] The lid and the upper or lower frame may be provided with
appropriate catches and closure elements. They may also be provided
with a tamper evident closure indication. The lower frame or upper
frame may also be provided with a scoop holder and levelling
portions. These may extend inwards into the access opening. It will
be understood that a scoop holder may also be provided in the
lid.
[0024] The invention further relates to a package comprising a lid
structure as described above applied to a container having a
peripheral wall extending to an upper edge and defining a product
containing space, the lower frame being connected to the upper edge
of the container. The package may have a generally square or
rectangular outer profile with rounded corners. The volume of the
package may be between 0.5 litre and 3 litres, preferably around
1.5 litres and the access opening preferably has a minimum
dimension of at least 70 mm, more preferably around 100 mm and an
area of at least 100 cm.sup.2.
[0025] Preferably, the package comprises a membrane seal for
sealing the product containing space prior to use. The membrane
seal may comprise a metal or plastics-metal foil or may be a
plastics-only foil. The membrane seal is a gas-tight seal. In this
context, it will be understood that a gas-tight seal is a seal that
substantially prevents passage of gas into or out of the container
during prolonged periods of storage. Preferably, it is an oxygen
barrier seal, preventing diffusion of oxygen into the sealed
container. The oxygen permeability of the seal may preferably be
less than 2.0 cm.sup.3/m.sup.2/day and more preferably may be less
than 0.5 cm.sup.3/m.sup.2/day. The membrane seal may be removed in
its entirety prior to use or may comprises a weakened tear line
defining an opening region, and a pull tab. The membrane seal may
be provided at various locations but most preferably, the membrane
is sealed across the upper edge of the container. In particular, it
will be understood that thermoformed tubs generally have an
outwardly extending flange forming the upper edge and the membrane
may be sealed across the flange. In an alternative embodiment, the
membrane may be sealed to the lower frame to close the opening. In
that case, the skilled person will understand that the connection
between the lower frame and the upper edge of the container must be
a gas-tight sealed connection.
[0026] In a most preferred embodiment, the container is or
comprises a thin-walled thermoformed tub having a wall thickness of
less than 0.5 mm. By the use of a thin walled thermoformed tub, the
amount of material required for forming the body of the container
is limited. Furthermore, the lower frame of relatively thicker
plastic material provides the required support to the relatively
thin material of the peripheral wall, allowing effective connection
to the upper frame. In this context, relatively thin is understood
by the skilled person to be with respect to the frame material. The
tub may be manufactured to have a wall thickness that is adequate
to provide the barrier properties and strength required. The
thickness of the wall may be between about 0.10 mm to 0.60 mm,
preferably between 0.2 and 0.40 mm. It will be understood that the
wall thickness may vary over the cross-section, being generally
thicker at the rim and thinnest at side walls. The values given
above for the thickness of the wall are intended to designate the
thickness of the side walls, which is usually the point of minimum
thickness. The lower frame may be significantly thicker, measured
at its smallest dimension and may have a thickness sufficient to
ensure a secure mechanical connection with the upper frame. The tub
may be manufactured of any appropriate material capable of being
thermoformed. A most suitable material is polypropylene. However,
other polymer materials such as polyethylene terephthalate (PET) or
polyethylene (PE) can be used as well. Multi layer materials may
also be used, subject to the requirements of recycling. The lower
frame may be permanently connected to the upper edge of the
container, preferably by welding.
[0027] Advantageously, the package consists of a single material
class for the purposes of recycling. This includes the tub, the
upper and lower frames and the lid. The membrane seal may be of the
same material although, given that it is removed on opening, it may
also be recycled separately.
[0028] Additionally, the container may further comprise a carton
sleeve enveloping and supporting the thermoformed tub. The carton
sleeve may fit closely to the tub with an interference fit and may
provide the necessary strength to the peripheral wall in order to
be form stable. In other words, the thin plastic material of the
peripheral wall may have insufficient strength alone to adequately
maintain the shape of the tub e.g. when stacking containers on each
other. By combining this with a carton sleeve, improved strength
may be achieved. The respective layers may be separated for
recycling. The sleeve may comprise carton of 50 to 400 g/m.sup.2,
preferably 100 to 300 g/m.sup.2. The sleeve may be open at the
bottom but preferably extends under the base of the tub.
[0029] According to one embodiment, the package may have a
generally square or rectangular outer profile with rounded corners.
The volume of the package may be between 0.5 litre and 3 litres,
preferably around 1.5 litres and the access opening preferably has
a minimum dimension of at least 70 mm more preferably around 100 mm
and an area of at least 100 cm.sup.2. The overall length of the
package may be between 150 mm and 250 mm, preferably about 185 mm.
The width of the package may be between 100 mm and 150 mm,
preferably around 120 mm. The package may be available in multiple
heights according to volume required, varying from 80 mm to 150
mm.
[0030] The package as described is particularly suitable for
containing a quantity of powdered nutritional product which can be
effectively sealed within the product containing space. Preferably
the powdered nutritional product comprises infant milk formula.
[0031] Preferably, a scoop is provided within the package and may
be located above the membrane seal prior to use. It is also
conceivable that a scoop is integrally formed with the lid
construction and separated at first use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The features and advantages of the invention will be further
appreciated upon reference to the following drawings of a number of
exemplary embodiments, in which:
[0033] FIG. 1 shows a package according to the present invention in
partly exploded perspective view;
[0034] FIG. 2 shows a perspective view of the package of FIG. 1
with closed lid;
[0035] FIG. 3 shows a perspective view of the package of FIG. 1
with opened lid;
[0036] FIG. 4 shows a partial cross-section through the package of
FIG. 2 along line IV-IV;
[0037] FIGS. 5a to 5c show cross-sectional views similar to FIG. 4
during connection of the upper frame; and
[0038] FIGS. 6a to 6c show cross-sectional views taken in direction
VI-VI in FIG. 3 during closure of the lid.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0039] FIG. 1 shows a partially exploded view of a package 1 having
a lid structure 3 according to a first embodiment of the invention.
The package 1 comprises a container in the form of a tub 2, a
sleeve 4 and a membrane seal 6 and the lid structure 3 includes a
lower frame 8, an upper frame 10 and a lid 12.
[0040] The tub 2 is thermoformed of relatively thin polypropylene
material and has a base 14 and a peripheral wall 16 defining a
product containing space 20. The peripheral wall 16 extends to an
upper edge 18 having an outwardly directed flange 19. The sleeve 4
is formed of carton and has wall 22 and a bottom 24. Lower frame 8
is an annular ring having an upstanding first sealing rim 48
surrounding an opening 26 of a similar dimension to the product
containing space 20. Between the first rim 48 and the opening 26
are located detent openings 46, the function of which will be
further explained below. The upper frame 10 is also in the form of
a ring and is provided with barbs 40 extending downwardly. The
lower frame 8 and upper frame 10 are also made of polypropylene
although it will be understood that other appropriate materials
could be employed. The membrane 6 includes a tear line 28 defining
an opening region 30 and includes a pull tab 32.
[0041] FIG. 2 shows a perspective view of the package 1 of FIG. 1
in the assembled state with the lid 12 closed. A catch 36 on the
front edge of the lid 12, engages with a rib 38 on the upper frame
10 to maintain the lid 12 closed. The lid 12 and upper rim 10 are
also made of polypropylene.
[0042] FIG. 3 shows a perspective view of the package 1 of FIG. 1
in the assembled state with the lid 12 open and the membrane
removed to provide access to the product containing space 20. A
scoop 42 is held within the lid 12 by clips 44 and can also be
positioned in a scoop holder 50 integrally formed with the lower
frame 8. Also visible are hinges 11 allowing pivoting connection
between the lid 12 and the upper frame 10.
[0043] FIG. 4 is a perspective cross-section along line Iv-Iv of
FIG. 2. As can be seen, the membrane 6 is attached across the
flange 19 of the tub 2 and sandwiched by the lower frame 8 which
overlies the flange 19. The flange 19, membrane 6 and lower frame 8
are all welded together to form a single relatively rigid rim
structure. Upper frame 10 is mechanically engaged with the lower
frame 8 by the downwardly extending barbs 40 that engage through
the detent openings 46 in the lower frame 8. As can also be seen in
this view, sleeve 4 closely engages against the peripheral wall 16
of tub 2, extending up to beneath the flange 19 to provide
additional support. This allows the upper rim 10 to be snapped into
the lower rim 8 without causing deformation or collapse of the tub
2.
[0044] According to an important aspect of the invention, the lid
structure 3 is provided with two seals. A circumferential first
seal is formed by the upstanding first sealing rim 48 which engages
with a downwardly extending first groove 54 on an underside of the
upper frame 10. A circumferential second seal is formed by an
upstanding second sealing rim 56 on the upper side of the upper
frame 10 which engages with a downwardly extending second groove 58
on the underside of the lid 12. Lead-in webs 60, 62 are located on
either side of the first groove 54 and second groove 58
respectively.
[0045] FIGS. 5a to 5c show cross-sections at the location of FIG. 4
with the upper frame 10 in the process of being connected to the
lower frame 8. FIG. 4a shows the upper frame 10 entering into
initial engagement with the lower frame 8. The lead-in webs 60 of
the first groove 54 engage against the upstanding first rim 48 and
guide it towards the first groove 54. The barb 40 has entered into
the detent opening 46.
[0046] In FIG. 5b, the upper frame 10 has been pressed downwards
onto the lower frame 8. This may be achieved by pressing on the lid
12. According to an important design consideration, on pressing on
the lid 12, the force F is applied against the upper frame 10 by
the lead-in webs 62 of the lid 12. In this manner, additional
pressure or deeper engagement of the second rim 56 into the second
groove 58 is avoided. As the upper frame 10 is pressed downwards,
the first rim 48 enters the first groove 54 and the barb 40 flexes
into the detent opening 46.
[0047] FIG. 5c shows the upper frame 10 fully engaged with the
lower frame 8 and the barb 40 locked in the detent opening 46. At
this stage removal of the upper rim 10 is not possible without
application of considerable force and breakage of the package. It
is noted that the barbs 40 protrude into the interior of the tub 2
and cannot therefore be accessed from outside the package 1. It may
also be noted that in the fully assembled position, the first rim
48 has not bottomed out in the first groove 54. This ensures that
due to manufacturing tolerances, the barb 40 will not be impeded
from connecting.
[0048] In this view it can also be seen that the upper frame 10 has
an external circumferential skirt 66 and the lid 12 has an exterior
surface 64. The exterior surface 64 and the skirt 66 are co-planar
in the closed position of the lid 12. In other words, both of the
lid 12 and upper frame 10 have external surfaces that blend
smoothly together at this location. Additionally, the lower frame 8
has a peripheral surface 68 and the peripheral surface 68 and skirt
66 are also co-planar when the upper frame 10 and lower frame 8 are
connected together as shown in FIG. 5c.
[0049] FIGS. 6a to 6c show cross-sections in the direction VI-VI of
FIG. 3 with the lid 12 in various stages of closure onto the upper
frame 10. In FIG. 6a, the lid 12 is in the open position supported
by hinge 11. As can be seen, the position of the hinge 11 is at a
radially inwards position with respect to the skirt 66 of the upper
frame 10. This means that when packages 1 are stacked adjacent to
one another, the hinge 11 does not protrude outwards and impede
close stacking. It is also less likely to be caught or snag
accidentally. It is also noted that at this position, there are no
lead-in flanges 62 supporting the second groove 58 and an inner
wall 58A is longer than an outer wall 58B of the second groove
58.
[0050] FIG. 6b shows the lid 12 in a partially closed position with
the upstanding second rim 56 engaging with the inner wall 58A of
the second groove 58. This contact occurs when the lid 12 is still
at an angle of around 20.degree. with respect to the upper frame
10. The downward extent of the inner wall 58A beyond that of the
outer wall 58B ensures that the second rim 56 is guided into the
second groove 58. In this case, the extended inner wall 58A acts as
a lead-in structure and for this reason, no lead-in flanges 62 are
required in this region. In fact, the absence of lead-in flanges 62
allows the inner wall 58A to more easily flex as the angle between
the lid 12 and the upper frame 10 changes. Furthermore, the angular
engagement on closing the lid 12 prevents the second rim 56 from
entering into the second groove 58 in a linear manner. The lead-in
webs 62 on the lid 12 assist in guiding this angled entry, ensuring
a progressive engagement of the second rim 56 into the second
groove 58, starting from the rear edge of the lid 12 adjacent to
the hinge 11 and progressing around the circumference to the front
edge of the lid 12 adjacent to the catch 36. In addition to
assisting in guiding the second rim 56 into the second groove 58,
the lead-in webs 62 also support the second groove 58 and help
maintain its position. Because of the additional support provided
by the lead-in webs 62, the structure forming the second groove 58
can be made more flexible allowing the closing action to be
smoother. As discussed above, the manufacturing tolerances for the
positions of these features is determined by the overall dimension
of the opening 26.
[0051] FIG. 6c shows the lid 12 in the closed position, with the
upstanding second rim 56 engaged with the second groove 58. As
described already above, full engagement of the second rim 56 into
the second groove 58 is avoided and the closed position of the lid
12 is defined by abutment of the lead-in webs 62 with the upper
frame 10 and the exterior surface 64 engaging onto the skirt
66.
[0052] Thus, the invention has been described by reference to
certain embodiments discussed above. It will be recognized that
many modifications in addition to those described above may be made
to the structures and techniques described herein without departing
from the spirit and scope of the invention. Accordingly, although
specific embodiments have been described, these are examples only
and are not limiting upon the scope of the invention.
* * * * *