U.S. patent number 3,884,382 [Application Number 05/320,897] was granted by the patent office on 1975-05-20 for container closures.
This patent grant is currently assigned to The Metal Box Company Limited. Invention is credited to Martin Frank Ball.
United States Patent |
3,884,382 |
Ball |
May 20, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Container closures
Abstract
An easy opening container member such as a can end, especially
for a container containing pressurised products, comprises a wall
having an orifice closed by a plug which is an integral part of a
plastic pull tab; the free end of the plug is upset to form a rivet
head which secures the pull tab to the wall and closes the orifice,
whilst a layer of metal foil covers and is bonded to the back of
the wall and the rivet head, preferably by a heat sealable
adhesive. In manufacture of the container member, the plug is
inserted and the foil laid on, and pressure, with heat if
necessary, is applied so as to form the rivet head and bond the
foil layer to the other components in one operation.
Inventors: |
Ball; Martin Frank (Welwyn
Garden, EN) |
Assignee: |
The Metal Box Company Limited
(London, EN)
|
Family
ID: |
9708934 |
Appl.
No.: |
05/320,897 |
Filed: |
January 4, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
220/272; 53/412;
53/489; 53/478; 413/14 |
Current CPC
Class: |
B65D
17/506 (20130101); B65D 17/503 (20130101); B65D
2517/0013 (20130101); B65D 2517/5032 (20130101); B65D
2517/5081 (20130101) |
Current International
Class: |
B65D
17/00 (20060101); B65D 17/50 (20060101); B65d
031/00 (); B65d 033/00 () |
Field of
Search: |
;220/53,54,27,90.6,48
;113/121A,121C ;229/7R ;222/541 ;53/39 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hall; George T.
Attorney, Agent or Firm: Diller, Brown, Ramik &
Wight
Claims
I claim:
1. An easy opening container member comprising a wall having a
dispensing opening therein, a closure of plastics material
including a plug portion of an outline corresponding to the outline
of said dispensing opening and an integral elongated tab portion,
said plug portion extending through said dispensing opening with
said tab portion overlying an outer surface of said wall and
tightly engaging said wall around said dispensing opening, said
plug portion terminating in a rivet head in the form of a radially
extending integral flange in molded engagement with an inner
surface of said wall and retaining said plug portion in place, a
layer of heat sealable adhesive over said rivet head and
surrounding adjacent portions of said wall inner surface, and a
layer of metal foil underlying said rivet head and said surrounding
adjacent portions of said wall and bonded thereto by said adhesive,
said adhesive layer and said metal foil layer being molded in the
area of said rivet head to define a receptacle for said rivet head,
and said rivet head being molded in accordance with the molding of
said layers.
2. A container member according to claim 1, constituting an end
member wherein the said wall has peripheral means for securing the
end member to a container body.
3. A method of making a container member, comprising the steps of
inserting, through an orifice of a container member wall, a plug
portion of a closure of plastics material comprising an elongate
tab portion having said plug portion integral therewith and
projecting transversely therefrom, so that said tab portion
overlies one face of said wall, applying a layer of metal foil over
at least a part of the opposite face of said wall defining said
orifice, and, after said foil layer has been so applied and the
plug portion so inserted, molding said foil layer and
simultaneously upsetting the free end of the plug portion to form a
rivet head formed in accordance with said molded foil layer and
having a flange overlying said opposite face adjacent the orifice
whereby to close the orifice and secure the closure to said wall,
and bonding the foil layer to said opposite face and to the rivet
head.
4. A method according to claim 3, wherein the step of upsetting the
free end of the plug portion is effected by applying heat to the
foil so that heat is transmitted through the foil to said free end,
and by applying pressure to upset the free end so heated.
5. A method according to claim 4, wherein said heat and pressure
are applied simultaneously.
6. A method according to claim 3, wherein the step of applying the
foil layer include applying said layer with a layer of adhesive
between the foil and said wall for bonding the foil layer to said
wall.
7. A method according to claim 6, wherein the adhesive is a heat
sealable adhesive, the step of upsetting the free end of the plug
portion being effected by applying heat to the foil so that heat is
transmitted through the foil to said free end and to said adhesive,
and by applying pressure to upset the free end so heated and to
press the foil layer, adhesive layer and wall firmly together.
8. A method according to claim 6, wherein the step of applying the
foil layer comprises applying the foil layer with said adhesive
layer overlapping said orifice for subsequently bonding the foil
layer to the rivet head.
9. A method according to claim 6, wherein the adhesive layer is
applied over the foil layer before the foil layer is applied over
said wall.
Description
BACKGROUND OF THE INVENTION
This invention relates to containers and container members of the
kind wherein pulling a pull tab causes an orifice of the container
or container member to be uncovered. It also includes within its
scope a container including a said container member and a method of
making said container member or container. Containers of the above
kind are often called "easy opening" containers.
DESCRIPTION OF THE PRIOR ART
Known containers of the above kind include those which are commonly
called "easy opening" containers, and which fall generally into
four main types, in all of which uncovering of the orifice actually
opens the container ready for the contents thereof to be
removed.
In one said type, the container has a metal end wall having an
integral removable portion defined by a score line, a metal pull
tab being secured to the removable portion and adapted to break the
score line by direct contact when the pull tab is pulled sharply
upwards to engage, by lever action, a nose portion thereof with the
score line. The orifice does not exist until the score line is
broken. This type of closure requires the removable portion to be
large enough for the pull tab to be attachable securely thereto,
for example by soldering or by means of a "rivet" formed integrally
with the removable portion and engaging in a hole in the pull tab.
It is not suitable where a small orifice is required, e.g., a
circular hole for pouring liquids from the container.
In another known type of easy-opening container, the container wall
has just such a small hole, pre-formed in the wall and closed by a
removable rubber bung. This is not generally satisfactory because
it is difficult to provide a satisfactory seal, especially where
the contents of the container are to be pressurised.
A third known type of easy-opening container utilises a strip of
metal, which may be foil or thicker than foil, or of plastics
material, bonded peelably to the outside of the container wall so
as to obscure a pre-formed orifice therein. This form of closure is
again not suitable for use with pressurised liquids.
A fourth known type of easy-opening container consists of a number
of variations that have been proposed for improving on the sealing
integrity of the third type mentioned above. For example, U.S. Pat.
No. 2,870,935 (Houghtelling) describes a flat plastic strip, to
serve as a pull tab, laid flat on top of a metal can end panel to
cover a hole in the can end panel, a film of the same plastic
material being applied on the underside of the strip to fill the
hole and form a key securing the strip to the end panel. This
suffers from the disadvantage that retention of the pull tab on the
end panel, and sealing integrity, depend entirely on the ability of
the material of the film to become and remain bonded securely to
the strip over the area of the hole and also to the metal
surrounding the hole. This is difficult to achieve in practice
especially in mass production.
Another container of the same general type is described in U.S.
Pat. No. 3,241,708 (Ronci), and has a can panel designed so that
when opened there shall be a relatively large opening therein. For
this purpose, part of the end panel itself consists of a separate
somewhat flat member of plastic fitting in the said opening which
is formed in the metal with a sharp downwardly directed edge. The
flat plastic member has an integral pull tab, and is secured to the
metal of the end panel simply by means of a layer of plastic film
applied across the underside of both parts of the end panel and
bonded thereto. The film layer also provides a measure of sealing,
but this arrangement suffers from the disadvantage that the sharp
edge of the metal, which is necessary for breaking the plastic
film, when the pull tab is lifted, deforms the film abruptly and
provides a potentially dangerous source of weakness which means
that effective sealing in large quantities of cans can never be
guaranteed. It also suffers from the disadvantage that the flat
member must be accurately made to fit in the aperture so that on
the one hand it is not loose and, on the other hand, it is not too
tight so as to tend by its own resilience to spring out of the
aperture. This again would be difficult to guarantee in mass
production. Such a container is also likely to be somewhat
expensive, and aesthetically unpleasing, especially since the flat
member is rather thick and bulky.
Yet another example of this fourth general type of easy-opening end
is described in British Patent Specification No. 1,059,406, and
comprises a rigid, soft metal plug, again made flat and forming
part of the end panel itself, the remainder of the end panel being
of metal and having a relatively large aperture into which the plug
is recessed, the plug being swaged to the edge of the aperture to
secure it therein. Sealing is effected by an adhesive sealing
compound applied to the underside of the end panel around the
aperture and overlapping the underside of the swaged plug. A
separate pull tab is secured to the soft metal plug, which is
intended to deform out of the aperture when the pull tab is lifted.
This type of can end is expensive to produce and unsuitable for
small pouring orifices such as those for which the present
invention is intended.
British Patent Specification No. 1,195,619 describes yet another
easy-opening can end of the same general type, and involves the
securing of projecting plugs of a plastic pull tab, in holes formed
in a metal can end panel, by means of a layer of adhesive applied
over the back of the end panel and over the plug. A layer of foil
is laid over the adhesive. In this arrangement, the pull tab merely
rests in the holes and is secured only by the adhesive, albeit
reinforced by the foil, and sealing integrity relies entirely on
the foil and adhesive, there being no particular seal between the
plug itself and the hole. Furthermore, the can end panel is formed
around each hole with a bead having a sharp cutting edge which is
required for rupturing the adhesive and foil when the pull tab is
lifted, and a thin portion of adhesive is provided to define a zone
of weakness to permit such rupture. This further endangers the
sealing integrity and pressure-retaining ability of the container,
especially under mass production conditions. Again, in this
connection the holes and the pull tab must be made very accurately
to ensure reasonable quality of the can end, and this would tend to
make such an end relatively expensive.
The said fourth type of known easy-opening container, as
exemplified above, can be summarised as one having an end member in
which a layer of suitable sealing compound is applied to the rear
or inner surface of the end panel or container wall so as to
overlap the periphery of an opening in the wall, whereby to bond to
the wall the pull tab or strip which closes the opening.
The known examples discussed above are, among other disadvantages,
either expensive, and/or unsuitable for small orifices, or do not
exhibit satisfactory sealing qualities, especially when made in
mass production for retaining pressurised products such as
carbonated beverages. It is noted especially that the pull tabs are
not secured positively by an integral portion thereof to the end
panels, thus always giving rise to the possibility of accidental
fracture causing the pull tab to break away, causing leakage or
inability to open the container or both.
OBJECTS OF THE INVENTION
The following are among the objects of the present invention (not
necessarily in order of importance) in the provision of an
easy-opening container member which:
is adapted to close a small orifice in a container wall;
provides improved sealing integrity;
is suitable for containing pressurised liquids;
provides a seal not only between the container wall and an element
integral with the pull tab but also further sealing behind the
container wall;
has the pull tab positively secured to the container wall by an
element integral therewith;
has the orifice filled by an element of the pull tab without
requiring accurate manufacture to ensure satisfactory
pressure-retention and sealing qualities;
is strong against accidental rupture or other accident such as to
break off the pull tab or destroy the seal;
does not have any sharp metal edge or other feature deliberately
creating a weakness such as to endanger the seal;
requires only a simple flat panel for insertion of the pull tab
therein;
uses only a minimum amount of material compatible with other
objects;
is simple and inexpensive to manufacture; and is suitable for mass
production with satisfactory consistency of quality.
SUMMARY OF THE INVENTION
The invention provides a container member, or a container including
such a member, wherein the said container member comprises a wall
in which an orifice is formed, the orifice being closed by a plug
portion formed integrally with a plastic pull tab. The member
consisting of plug portion and pull tab is referred to herein and
in the claims as a closure. The plug portion extends through the
orifice and projects behind the container wall, and its free end is
in the form of a rivet head having a flange overlying the back face
of the wall (i.e. the face opposite that overlain by the pull tab)
so as to secure the pull tab positively to the container wall by
means of its integral plug portion. A layer of metal foil overlies,
and is sealingly bonded to at least part of the back face of the
wall and also to the rivet head.
In another aspect, the invention provides a method of making such a
container member, wherein the plug is inserted through the orifice;
the foil is applied over the back face of the wall; and pressure,
with heat if necessary, is applied so as in a single operation to
upset the material of the free end of the plug portion (and so form
the rivet head) and also to bond the foil to the container wall and
to the rivet head.
Seals are thus provided, not only between the plug portion itself,
including the flange, and the wall around the orifice, but also by
the foil being bonded over the edge of the rivet head.
Preferably, the foil layer is sealingly bonded to said wall by an
adhesive layer. It may also be bonded to the rivet head by the
adhesive layer.
The container wall may be of metal, though it may be of a suitable
plastic material. Use of an adhesive layer will be necessary at
least where the wall is of metal.
Use of heat for the upsetting and bonding operation is preferable,
in that heat is transmitted through the foil to said free end, and
by applying pressure to upset the free end so heated.
The adhesive, where used, is preferably a heat sealable adhesive,
the step of upsetting the free end of the plug portion being
effected by applying heat to the foil so that heat is transmitted
through the foil to said free end and to said adhesive, and by
applying pressure to upset the free end so heated and to press the
foil layer, adhesive layer and wall firmly together. Thus
application of heat and pressure causes the foil, the wall and the
closure to become firmly sealed together with the adhesive, in the
same operation as the formation of the rivet head.
The adhesive layer may be applied so that it overlaps the orifice,
so that subsequently the rivet head as well as the wall is bonded
by adhesive to the foil.
In one form of the method according to the present invention, the
adhesive layer is applied to the foil and the foil and adhesive
layers are therefore applied together to the container wall, either
before or after the closure plug portion is introduced into the
orifice. Alternatively the adhesive layer may be applied to the
container wall, so that when the foil layer is applied it is
applied to the adhesive layer already on the wall.
The adhesive layer may be applied to the wall before or after the
closure plug portion is introduced into the orifice. It will,
however, be understood that if the adhesive is applied to the wall
before the introduction of the plug portion to the orifice, there
will be no adhesive between the rivet head subsequently formed and
that part of the foil layer which covers the rivet head, unless
adhesive is applied separately to the free end of the closure plug
portion. This may be done before or after introduction of the plug
portion into the orifice. If adhesive is applied to the wall after
such introduction, it can be applied over the free end of the plug
portion at the same time.
It is essential that the rivet head be bonded to the foil layer,
either by the use of adhesive between them, or by choosing the
closure material so that, when heat is applied to upset the
material of the plug portion of the closure, this material becomes
bonded directly to the metal foil. In the latter case it is not
necessary that the adhesive layer shall extend over the rivet head;
in such a case the adhesive, if applied directly to the wall, will
not also be applied to the free end of the plug portion; and if
applied to the foil, the adhesive will be applied leaving a
cricular area of the foil uncovered by adhesive, this circular area
corresponding approximately to the orifice in the container wall
when the foil carrying the adhesive layer is applied to the
wall.
Where the adhesive layer does extend over the free end of the plug
portion of the closure, the application of heat will melt or soften
the adhesive and at the same time soften the material of the plug
portion. There may therefore be some fusion or mixing of the plug
portion material with the adhesive, thus creating a particularly
strong bond, and, especially in the region of the outer periphery
of the rivet head, a good seal.
The foil layer may be of aluminium or iron or any other metal
compatible with the intended contents of the container. A layer of
protective material such as a lacquer of known kind may be applied
over the exposed surface of the foil, or over the container end
wall surface after the foil has been applied thereto and the
application of heat completed.
It will be realised that, in a container member according to this
invention, the closure may be of such a material and so dimensioned
that the rivet head flange will become severed from the remainder
of the plug portion when the tab portion is pulled outwardly.
However, the closure may instead be made so that the flange is
sufficiently narrow and flexible to be deformed and forced up and
out of the orifice without becoming severed from the remainder of
the plug portion. In either case, the foil layer is ruptured around
approximately the periphery of the rivet head when the closure is
pulled upwards, by virtue of the bond between the closure and the
foil. Thus removal of the closure also makes a hole through the
foil layer, so bringing the interior of the container into
communication with the outside atmosphere.
It will also be understood that, while it is perferable that the
rivet head shall sealingly close the orifice in the practice of the
present invention, it may in some cases be unnecessary to provide a
seal in this way provided the seal provided by the foil and
adhesive layers is sufficient.
Other objects and advantages of the invention will be apparent from
the description, given by way of example only, of an embodiment of
the invention.
IN THE DRAWINGS
FIG. 1 is a top plan view of a can end provided with a closure
incorporating features of the invention, FIGS. 2 to 5 being
sectional views on a larger scale taken on line II--II in FIG.
1;
FIG. 2 shows components of the can end before assembly;
FIG. 3 shows a stage in the assembly of the can end;
FIG. 4 shows the can end at the end of the assembly process;
FIG. 5 shows the can end being opened; and
FIG. 6 shows a can including the can end.
With reference to the drawings, a container comprises a generally
cylindrical metal beer can, FIG. 6, having a cylindrical body 1 and
a separate container member consisting of a can end 11 secured in
conventional manner to the can body 1 by a peripheral seam 12. The
can end 11 includes a metal end panel or container wall 13 through
which there is a relatively small circular pouring hole or orifice
14.
The hole 14 is closed by a one-piece closure 15 having an elongate
generally flat tab portion 16, one end of which is typically formed
into a finger ring 17, and which overlies the top face 84 of the
wall 13. A plug portion 18, integral with the tab portion 16,
extends transversely to the plane 19 of the latter at the end
thereof remote from the finger ring. The plug portion 18 is
cylindrical to conform with the shape of the hole 14, and its
length and diameter are such that it can be inserted easily but not
too loosely into the hole 14 with its free end 20 projecting behind
the wall 13.
The closure 15 is preferably of resilient plastics material, for
example polypropylene.
In the method of making the container member or can end 11, the
components shown in FIG. 2 are assembled together in the following
manner. A sheet or strip 80 of alumimium foil, to one surface of
which a layer of heat-sealable adhesive 81 has been previously
applied, is applied over at least part of the inner surface 82 of
the end panel 13, (i.e., the surface or face opposite the face 84),
so as to overlap the hole 14 with the adhesive layer 81 between the
foil 80 and the panel 13, as shown in FIG. 3. The hole 14 is then
closed by inserting the plug portion 18 of the closure in the hole
14. A heated pressure member or mould tool 83, FIG. 4, is now
brought into contact with the foil 80, applying heat to the foil so
that heat is transmitted through the foil to the plug portion 18.
The pressure member is conventionally constructed and arranged in a
conventional press of any suitable, well-known kind.
The member 13 is held by suitable means, not shown, such as a clamp
of conventional construction, so that the pressure member 83 can
apply pressure to it as well as heat. This simultaneous application
of heat and pressure upsets the free end 20 of the plug portion and
so forms a rivet head 22 which closes the hole 14 and secures the
closure 15 to the end panel 13. At the same time the adhesive layer
81 is activated to bond the foil layer 80 to the end panel 13 and
to the rivet head 22.
The pressure member 83 is then withdrawn and the completed can end
11 is subsequently attached to the can body. The completed can end
in this example is as shown in FIG. 4, the foil layer 80 being
sealingly secured by the adhesive layer 81 over the surface 82,
overlying the rivet head 22 and being sealingly bonded to it.
The plug portion 18 is deformed by the upsetting operation so that
the rivet head 22 has a flange 23 extending from and around the
shank 24 which constitutes the remainder of the plug portion, so as
to overlie the wall 13 around the hole 14 and sealingly close the
lower end of the hole. Some adhesive from the layer 81 may, during
the application of heat and pressure by the mould tool 83, find its
way between the flange 23 and wall 13, so improving the seal still
further.
To open the container, an outward tensile force, as indicated at A
in FIG. 5, is applied to the tab portion 16, by pulling up on the
finger ring 17 in a direction such as to tend to dislodge the plug
portion 18 from the hole 14. This, in this example, causes a
circumferential fracture to occur as indicated at 25, whereby the
flange 23 is severed from the shank 24 so that the latter is
dislodged outwardly. At the same time, the foil and adhesive layers
80, 81 are ruptured adjacent the flange 23 as shown in FIG. 5, so
that the closure 15, without the flange 23 but with a portion of
the foil still attached to it, can then be lifted off to expose the
open hole 14.
It is to be understood that the mode of rupture of the foil and
adhesive layers, and of the rivet head if the latter is ruptured,
is by shear action entirely or predominantly. Some slight cutting
action may be provided by the raw edge of the hole 14, but such
cutting is only incidental, shearing being in effect the means by
which the seal is broken to release the closure.
The adhesive layer 81, if provided, may be applied, by coating or
spraying or by overlaying a sheet of the adhesive material on the
surface 82 before the foil layer 80 is applied and preferably
before the plug portion 18 is inserted.
Although the present invention is suitable for containers for
pressurised liquids, it will be understood that it can be used with
containers for containing any product, liquid or otherwise,
pressurised, vacuum-packed or otherwise, which is compatible
chemically with the material of the closure and where the size of
the dispensing or venting orifice closed by the closure is required
to be relatively small.
* * * * *