U.S. patent application number 12/281024 was filed with the patent office on 2009-02-05 for container.
This patent application is currently assigned to CROWN PACKAGING TECHNOLOGY, INC.. Invention is credited to James Leslie Bullock, Paul Claydon, Robert Paul Dunwoody, Philip Alan Marriott.
Application Number | 20090032535 12/281024 |
Document ID | / |
Family ID | 36218920 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090032535 |
Kind Code |
A1 |
Dunwoody; Robert Paul ; et
al. |
February 5, 2009 |
CONTAINER
Abstract
A container (1) particularly for food products comprising a
metal can body (2) and a combination of a ring (12) and a foil
membrane (14), the combination being attached to the can body, in
which the ring is made of a plastics material, wherein the inside
diameter of the plastic ring is no less than the inside diameter of
the can body away from the attachment location of the ring on the
can body.
Inventors: |
Dunwoody; Robert Paul;
(Oxfordshire, GB) ; Marriott; Philip Alan;
(Oxfordshire, GB) ; Claydon; Paul; (Oxfordshire,
GB) ; Bullock; James Leslie; (Wiltshire, GB) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
CIRA CENTRE, 12TH FLOOR, 2929 ARCH STREET
PHILADELPHIA
PA
19104-2891
US
|
Assignee: |
CROWN PACKAGING TECHNOLOGY,
INC.
ALSIP
IL
|
Family ID: |
36218920 |
Appl. No.: |
12/281024 |
Filed: |
February 23, 2007 |
PCT Filed: |
February 23, 2007 |
PCT NO: |
PCT/EP2007/051771 |
371 Date: |
August 28, 2008 |
Current U.S.
Class: |
220/270 ;
156/69 |
Current CPC
Class: |
B65D 77/202 20130101;
B65D 21/0219 20130101; B65D 17/502 20130101; B65D 2517/5013
20130101; B65D 15/14 20130101 |
Class at
Publication: |
220/270 ;
156/69 |
International
Class: |
B65D 17/34 20060101
B65D017/34; B65B 7/28 20060101 B65B007/28 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2006 |
GB |
0604097.6 |
Claims
1. A container comprising: a metal can body, and a combination of a
ring and a foil membrane, the combination being attached to the can
body, the ring is formed of a material comprising a plastic the
inside diameter of the plastic ring is no less than the inside
diameter of the can body away from the attachment location of the
ring on the can body.
2. A container as claimed in claim 1, wherein the edge of the can
body to which the ring/foil membrane combination is attached
comprises an expanded portion, all or part of the ring locating
within the expanded portion, the inside diameter of the ring being
no less than the inside diameter of the unexpanded portion of the
can body.
3. A container according to claim 2, wherein the height of the ring
corresponds to the axial length of the expanded part of the can
body.
4. A container according to claim 1, wherein the ring is directly
bonded to the sidewall of the can body.
5. A container according to claim 1, wherein the ring comprises at
least one of polypropylene or modified polypropylene.
6. A container according to claim 5, wherein the modified
polypropylene comprises polypropylene grafted with maleic
anhydride.
7. A container according to claim 1, in which the plastic ring is
bonded permanently to the can body and the foil membrane is bonded
peelably to the ring.
8. A container according to claim 1 wherein the can body comprises
a curl or flange and the ring comprises a shoulder, the shoulder
extending into an outer peripheral wall which depends from the
shoulder over the outside of the can body curl or flange.
9. A container according to claim 8, in which the outer peripheral
wall comprises a hook portion which clips over the can body curl or
flange to retain the ring on the can body.
10. A container according to claim 1 wherein the ring comprises a
portion which projects upwardly to provide a rim, the base of the
container and the rim each being formed such that the base of a
first container may be located within the rim of a second
container.
11. A container according to claim 1, wherein the ring is provided
with a substantially flat bonding surface, and the foil membrane is
bonded to this flat surface.
12. A container according to claim 1, wherein the ring is provided
with a bonding surface inclined downwardly at an angle of up to
60.degree., and the foil membrane is bonded to this inclined
surface.
13. A container according to claim 1, wherein the ring is provided
with a bonding surface inclined downwardly at an angle of up to
45.degree., and the foil membrane is bonded to this inclined
surface.
14. A container according to claim 1, wherein the foil membrane is
cup shaped and the sidewall of the foil cup is bonded to the inner
sidewall of the ring.
15. A method of forming a container, the method comprising: forming
a metal can body; fixing a ring formed of a material comprising a
plastic permanently to the can body, the inside diameter of the
plastic ring being no less than the inside diameter of the can body
away from the attachment location of the ring on the can body; and
bonding a foil to the ring such that, in use, the foil may be
peeled from the ring for dispensing a product from the
container.
16. A method according to claim 15, wherein the can body is formed
with a radially expanded portion at one end of the can body, and
the plastic ring is fixed permanently to the can body such that all
or part of the ring is located within the expanded portion.
17. A method according to claim 15, in which the step bonding the
foil occurs before the step of fixing the ring such that the foil
is first bonded to the ring and the combined ring and foil is
subsequently fixed to the can body.
18. A container comprising: a metal can body, and a combination of
a ring and a foil membrane, the combination being attached to the
can body, the ring is formed of a material comprising a plastic,
the ring/foil membrane combination comprises a permanent bond
between the membrane foil and the ring and the foil is peelably
bonded to the inside of the can body sidewall.
Description
TECHNICAL FIELD
[0001] This invention relates to a container. In particular, it
relates to a container which comprises the combination of a can
body for products such as food, and a closure element. The
invention also includes a method of forming the combination of can
body and closure element.
BACKGROUND ART
[0002] Cans for the packaging food are typically of a two or three
piece form, comprising a tubular can body, either cylindrical or
irregular/polygonal in cross-section, with a base and closed by a
can end, diaphragm, film, screw top or other closure. The base may
be integral with the can body so as to form a so called two-piece
can body, or the can body may be formed from a tube of sheet metal
with the edges of the sheet metal joined by a welded side seam,
which is then closed at both ends to form a three-piece can.
[0003] Typical food cans which are closed by a can end, have
sealing compound in the curled edge of a cover hook portion of the
can end in order to provide a tight hermetic seam, usually known as
a double seam due to the two thicknesses of metal in the seam--one
from the can body and the other from the can end. A problem with a
three piece can body is that the welded side seam provides an
irregular sealing surface for seaming. The sealing compound needs
to be precisely and uniformly placed so that the resultant ring of
sealing compound within the seam has the right width, thickness and
position to ensure that the seam has the required tightness. Double
seam technology is a precise art, which relics on numerous factors
for seam integrity, of which the sealing compound is one important
feature.
[0004] Cans for other products may use different closure
arrangements; for example, a peelable foil is typically seated on
an intermediate metal ring which, in turn, is seamed to the can
body. Such can and ring combinations are expensive to manufacture
as the central disc from the ring element is generally scrapped,
leading to material wastage. Proposals such as those described
in
Patent Citation 0001: EP 1029613 A (IMPRESS GMBH & CO).
2000-08-23.
[0005] and
Patent Citation 0002: WO 2005063587 A (CROWN PACKAGING TECHNOLOGY
INC). 2005-07-14.
[0006] avoid wasting the centre of the ring, but include additional
manufacturing stages which, in turn, involve extra process time
and/or capital equipment costs.
Patent Citation 0003: EP 0819086 B (GRABHER, WERNER).
1998-12-23.
[0007] describes a semi-finished can which is open at one end and
closed at its other end by a cup-shaped foil membrane. The sidewall
of the foil cup extends in the direction of the can axis and is
bonded directly to the inside of the can wall. The foil may extend
over the can body edge, which has been formed into a hook or curl.
Although inexpensive to manufacture, unfortunately when cans closed
in this way are stacked, the pressure of the upper can bears
directly onto the foil, risking damage to the foil. In addition,
the foil is bonded to the can body over a side seam which presents
an irregular sealing surface as described above.
[0008] Another problem with
Patent Citation 0004: EP 0819086 B (GRABHER, WERNER).
1998-12-23.
[0009] is that the container is unsuitable for use with foods which
generate internal positive pressure within the can body during
processing as this tends to peel the foil from off the sidewall of
the container.
[0010] This invention seeks to overcome the problems of EP 0819086
B whilst still providing a container that is less expensive and
wasteful to manufacture than the ring and peelable foil membrane
closures described above.
DISCLOSURE OF INVENTION
[0011] This invention seeks to provide a can body and closure
element for closing by a variety of closure panels (can end,
diaphragm, disc etc.) at a reduced cost in comparison with
traditional peelable closures.
[0012] Accordingly, a first aspect of the invention provides a
container comprising:
a metal can body, and a combination of a ring and a foil membrane,
the combination being attached to the can body, in which the ring
is made of a plastics material, characterised in that the inside
diameter of the plastic ring is no less than the inside diameter of
the can body away from the attachment location of the ring on the
can body.
[0013] Use of a plastic ring is more economical than using a metal
ring from which the centre is generally discarded. The bond between
the ring/foil membrane combination and the can body provides a
strong connection to give a hermetic seal. Furthermore, the
ring/foil membrane combination covers any weld (for example, a
welded side seam in the sidewall of a 3 piece can) and the plastic
ring supports any container stacked on top, without risk of damage
to the foil membrane.
[0014] Ensuring that the inside diameter of the plastic ring is no
less than the inside diameter of the can body away from the
attachment location of the ring on the can body is beneficial in
maximising the opening aperture of the container and in enabling
full release of product from the container. The can body may have a
generally cylindrical profile, i.e. with a straight or tapered
sidewall. In such an embodiment, the ring may be retained by
contact between the ring and the exterior surface of the can body;
conveniently, retention of the ring on the can body is enabled by
the ring having an outer peripheral wall and a hook portion as
described below.
[0015] Preferably however, the edge of the can body to which the
ring/foil membrane combination is attached comprises an expanded
portion, all or part of the ring locating within the expanded
portion, the inside diameter of the ring being no less than the
inside diameter of the unexpanded portion of the can body. Usually
the height of the ring corresponds to the axial length of the
expanded part of the can body. Consequently, the inner sidewall of
the ring extends smoothly into the inner sidewall of the can body.
This is beneficial in enabling full release of product from the
container and is particularly useful for solid or semi-solid food
products, such as cooked meats, thick soups or pet food
[0016] In one embodiment, the ring is bonded permanently to the can
body and the foil membrane is bonded peelably to the plastic ring.
The ring may be formed from a conventional thermoplastic polymer,
such as polypropylene. The bonding between the ring and the can
body may be enhanced by selection of the coating on the can body;
for example, a film of heat sealable lacquer may be applied at the
interface between the ring and the can body or be precoated onto
the can body and/or the ring. The ring may be heat sealed to the
can body, for example using induction heating, with the application
of heat causing the heat sealable lacquer to form a bond between
the ring and the can body. When using induction heating to bond the
ring to the can body, the foil membrane is typically peelably
bonded to the ring subsequent to the bonding of the ring onto the
can body, thereby ensuring that any metal in the foil membrane will
not interfere with the induction heating process. The resulting
container is more easy to open by peeling than that of EP 0819086
B, which is not in peel mode for opening.
[0017] In a preferred embodiment, the ring is directly bonded to
the sidewall of the can body. The plastic ring may be made from a
thermoplastic polymer; it has been found beneficial for the plastic
ring to comprise polypropylene or modified polypropylene. The ring
may then be placed in position on the can body and suitable heating
means applied (for example, induction heating). The action of the
heating causes the surface of the ring itself to directly bond with
the surface of the can body, even when the can body surface
includes protective lacquers/coatings (for example, epoxy-based
coatings). Advantageously, the modified polypropylene comprises
polypropylene grafted with maleic anhydride. Such a modified
polypropylene has been found to form a strong bond with
conventional lacquers of the type commonly used on metal can bodies
to protect the metal substrate of the can body, such as epoxy-based
lacquers. Polypropylene is a non-polar material, whereas the
lacquers used to protect the metal substrate of a can body (e.g.
epoxy-based lacquers) are often polar materials. The addition of
maleic anhydride improves the ability of the non-polar
polypropylene of the plastic ring to bond with polar lacquers
provided on the can body.
[0018] The can body may comprise a curl or flange, and the ring may
include a shoulder which is adapted to extend over the can body
curl/flange. Preferably, the shoulder extends into an outer
peripheral wall which depends from the shoulder over the outside of
the can body curl/flange. Advantageously, the outer peripheral wall
comprises a hook portion so as to clip over the can body
curl/flange to retain the ring on the can body. The hook portion is
useful for retaining the ring in position on the can body if the
ring is to be fixed onto the can body by induction heating (or
other means involving application of heat to the ring), because it
compensates for any thermal expansion or contraction of the plastic
ring relative to the metal can body.
[0019] Conveniently, the shoulder includes a portion which extends
upwardly to provide a rim for handling and tab protection.
Preferably, the base of the container and the rim are formed such
that the base of a first container of the present invention may be
located within the rim of a second container of the present
invention, thereby enhancing the ability to stack the containers on
top of each other.
[0020] In one embodiment, the ring's shoulder is provided with a
substantially flat bonding surface, and the foil membrane is bonded
to this flat surface. In an alternative embodiment, the ring is
provided with a bonding surface inclined downwardly at an angle of
up to 60.degree., and the foil membrane is bonded to this inclined
surface. The provision of such an inclined bonding surface has been
found to enable retort processing of the container. When subject to
internal positive pressure during processing, the foil would expand
outwardly to form a curved profile. The inclined bonding surface
ensures that the foil membrane is mainly loaded in shear rather
than in peel when subject to internal positive pressure, thereby
inhibiting loss of seal between the foil membrane and the plastic
ring. More preferably, the bonding surface is instead inclined
downwardly at an angle of up to 45.degree..
[0021] The foil membrane usually includes a tab for gripping to
peel the foil membrane from the ring. Ideally, this tab is situated
towards one edge of the foil in order to reduce peel force
requirements.
[0022] Alternatively, the foil membrane may be formed in the shape
of a cup (i.e. cup-shaped) and the sidewall of the foil cup bonded
to the inner sidewall of the ring. In this embodiment, it is
beneficial for any tab to be situated away from the sidewall of the
cup-shaped foil to assist in peelable removal of the foil.
[0023] In a second aspect of the present invention, there is
provided a method of forming a container, the method
comprising:
forming a metal can body; fixing a ring of plastics material
permanently to the can body, the inside diameter of the plastic
ring being no less than the inside diameter of the can body away
from the attachment location of the ring on the can body; and
bonding a foil to the ring such that, in use, the foil may be
peeled from the ring for dispensing a product from the
container.
[0024] Preferably, the can body is formed with a radially expanded
portion at one end of the can body, and the plastic ring is fixed
permanently to the can body such that all or part of the ring is
located within the expanded portion.
[0025] Alternatively, the steps of fixing the ring and bonding the
foil may be reversed such that the foil is first bonded to the ring
and the combination of ring and foil is subsequently fixed to the
can body.
[0026] According to a third aspect of the present invention, there
is provided a container comprising:
a metal can body, and a combination of a ring and a foil membrane,
the combination being attached to the can body, in which the ring
is made of a plastics material, characterised in that the ring/foil
membrane combination comprises a permanent bond between the
membrane foil and the ring, and the foil is peelably bonded to the
inside of the can body sidewall.
[0027] In this aspect of the invention, the ring may include a tab
or ring pull for removing the ring and foil together as a single
entity from the container. The relative rigidity of the plastic
ring compared to the foil membrane may enable the container to be
recloseable by locating the ring/foil membrane combination back
onto the can body.
[0028] This aspect of the invention may also incorporate one or
more of the features described above for the first aspect of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Preferred embodiments of the invention will now be
described, by way of example only, with reference to the drawings,
in which:
[0030] FIG. 1 is a side section of a first embodiment of a
container according to the invention;
[0031] FIG. 2 is a perspective view of the container of FIG. 1;
[0032] FIG. 3 is a side section of a second embodiment of a
container according to the invention;
[0033] FIG. 4 is a perspective view of the container of FIG. 3;
[0034] FIG. 5 is side section of a third embodiment of a container
according to the invention;
[0035] FIG. 6 is a perspective view of the container of FIG. 5;
[0036] FIG. 7 is a side section of a fourth embodiment of a
container according to the invention;
[0037] FIG. 8 is a side section of a fifth embodiment of a
container according to the invention; and
[0038] FIG. 9 is a perspective view of the container of FIG. 8.
MODE FOR THE INVENTION
[0039] FIGS. 1 and 2 show a container 1. The container 1 is of a
so-called "three piece" type, comprising a cylindrical can body 2
that is closed at its lower end by a conventional closure 3. The
closure 3 is joined to the can body 2 by a double seam 4. The can
body 2 is radially expanded by an amount `a` (in this example,
approximately 2 mm) at its upper end to provide a stepped portion 5
and terminates in a flange or curl 6.
[0040] The can body 2 may be formed from a metal sheet which is
coated with a lacquer, polypropylene being dispersed within the
lacquer. The metal sheet may then be formed into a cylinder (for
example, by welding) to provide the can body. The welded side seam
thus formed on the can body is generally separately coated with a
similar internal lacquer or with a polypropylene powder.
Alternatively, the metal sheet could be coated with a conventional
lacquer and a specific lacquer, such as one including a dispersion
lacquer, used only for coating that part of the can wall and weld
which is to contact the plastic ring 12.
[0041] The upper end of the can body 2 is closed off by a closure
10. The closure 10 includes a plastic ring component 12, and a
diaphragm or foil 14 with a peripheral tab 16 for opening. The
plastic ring 12 is moulded into a first annulus 18 that is
substantially cylindrical and shaped to be seated within the
stepped portion 5. In the embodiment shown, the plastic ring 12 has
an internal diameter which is the same as that of the unexpanded
portion of the can body 2. This provides a smooth transition from
i) the inner sidewall of the unexpanded portion of the can body 2
to ii) the inner sidewall of the plastic ring 12, thereby
optimising product release. However, alternative embodiments may
have the plastic ring 12 having an internal diameter which is
greater than that of the can body 2 beneath the stepped portion 5.
In either case, the plastic ring 12 does not impede the release of
product from the container 1, but instead promotes full product
release. The plastic ring 12 is also typically of either
polypropylene for bonding to a polypropylene dispersion in the
internal can body coating, or modified polypropylene for bonding to
conventional lacquers.
[0042] The annulus 18 of the plastic ring 12 extends radially
outwardly into a flat shoulder portion 20 which, in turn, extends
outwardly and downwardly into a retention portion 22 and upwardly
into a rim 24. The plastic ring 12 may also be shaped (for example,
with a hooked portion) so as to be snapped into position around the
can body flange or curl 6 and thereby hide any exposed metal of the
flange or curl. The annulus 18 is permanently bonded to the can
body, for example by induction heating. The bonded region may also
include the curl or flange 6.
[0043] The foil 14 is bonded to the flat shoulder portion 20 which
forms a sealing surface of 1.0 to 2.5 mm in width. The centre
region of the foil 14 as shown in FIG. 1 is domed inwardly due to
negative pressure (so-called "vacuum") within the container
following filling or processing.
[0044] The container 1 of FIGS. 1 and 2 is typically formed in two
separate stages. In one stage, the can body 2 has the flange or
curl 6 formed around the periphery to which the plastic ring 12 is
to be bonded, and then the upper region of the can body 2 is
radially expanded to form the stepped portion 5. The plastic ring
12 is bonded to the can body 2 by induction heating, and the foil
14 then fixed to the plastic ring. The container 1 is filled
through its bottom end and the closure 3 seamed onto the filled
container. In this method, the foil 14 does not interfere with the
induction heating process and the induction heating does not
interfere with the peelable bond between the foil 14 and plastic
ring 12.
[0045] The example of FIGS. 3 and 4 is similar to that of FIGS. 1
and 2 but includes a shoulder portion 21 which slopes downwardly
from the horizontal by an angle .alpha. (in this example,
20.degree.). Downwardly extending or "barometric" shoulders are
preferred for containers in which the lidding material is deflected
by in-can pressure during processing of the food product in the
container and enables use in reel and spiral retorts (or similar
processes). By inclining the shoulder portion 21 downwardly, the
angle .alpha. becomes greater than the angle subtended by the
extremity of the lidding material in its outwardly domed position
when subject to positive internal pressure. As a result, the
sealing surface is predominantly loaded in shear rather than in
peel, which effectively doubles the burst pressure performance from
that of containers with flat shoulders (such as that of FIGS. 1 and
2) which would be loaded in peel mode when subject to positive
internal pressure. For barometric shoulders, preferred bonding
surface angles .alpha. are up to 45.degree. to give sufficient dome
size, although in theory angles .alpha. of up to 60.degree. are
possible.
[0046] Although the centre region of the foil 14 of FIGS. 3 and 4
has been shown with a plain surface, decoration for customisation
or beading for improving barometric performance may be used to
allow for movement of the foil 14 whilst avoiding foil
wrinkling.
[0047] This embodiment may be formed in the same way as that of
FIGS. 1 and 2. Of course, either of these two embodiments could use
a container drawn from a blank of sheet metal to form a sidewall
and integral base (i.e. no welded side seam), in which case the
plastic ring 12 and foil 14 may be formed as one component which is
subsequently bonded to the can body 2 after filling. Alternatively,
the ring 12 may first be bonded to the can body 2, the can filled
and the foil 14 then bonded to the plastic ring.
[0048] In the alternative container shown in FIGS. 5 and 6, like
features of the can body 2 are given the same reference numerals as
in FIGS. 1 to 4. The plastic ring 12 of this embodiment comprises a
shoulder 13 which extends over the edge of the can body (here shown
as a curl 6, although the edge may be unshaped or a simple flange)
and the annulus 18 is seated against and permanently bonded to the
inner wall of the can body 2 in the same manner as the embodiments
of FIGS. 1 to 4. However, in FIGS. 5 and 6, the foil 14 is peelably
bonded to the inner wall of the plastic ring 12, rather than to a
flat or downwardly inclined portion of the ring. In this
embodiment, the foil 14 defines a cup-shape profile. This avoids
the problems of direct welding of foil over a weld margin as arises
in processes such as that described in
Patent Citation 0005 EP 0819086 B (GRABHER). 1998-12-23.
[0049] Tab 16 of FIGS. 5 and 6 is bonded to the central part of
foil 14. This ensures that a customer peels the foil 14, rather
than trying to remove the whole of the permanently bonded plastic
ring 12 from the can body 2.
[0050] FIG. 7 shows an alternative container 1 which has a
generally cylindrical can body 2 terminating at its upper end with
flange or curl 6 at the edge of the can body. The ring 12 includes
a flat shoulder portion 20 which extends outwardly and downwardly
into a retention portion 22 and upwardly into a rim 24. The
retention portion 22 terminates in a hooked portion 25 which
partially extends underneath the flange or curl 6 to assist in
retaining the ring 12 on the can body 2. The ring 12 is permanently
bonded to the can body, with the bonded region including the
exterior surface of the curl or flange 6. As can be seen from FIG.
7, in this embodiment the plastic ring 12 does not extend down
along the interior surface of the can body 2, thereby avoiding the
need to provide an expanded portion on the can body. Consequently,
release of product from the resulting container is not impeded.
[0051] FIGS. 8 and 9 represent an embodiment of the invention in
which a plastic ring 30 is bonded permanently to the foil 14. As
clearly seen from FIGS. 8 and 9, the foil 14 is bonded to the
external sidewall of the plastic ring 30. The combination of the
plastic ring 30 and foil 14 is attached to the can body 2 by
peelably bonding the foil to the inner wall of the can body 2
around the upper sidewall 32 of the can body 2. The plastic ring 30
incorporates a large ring-pull style of tab 36 for ease of gripping
when removing the foil (and ring) from the container 1.
* * * * *