Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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: TETRA PAK INTERNATIONAL AB TP 496 ::
OPENING ARR~NGEMENT FOR PACKING CONTAINERS
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The present invention relates to an opening arrange-
ment for packing containers of the type wherein a part of
.~ the packing container wall which is openable by means of a
tearing thread is limited by an opening indication line.
It is customary fox an opening arrangement in a
- packing container wall of paper or laminated plastic mate-
rial to be formed with the help of a weakening line arranged
in the wall, which extends around an openable portion. When
~:~ the packing container is to be opened, this is usually done
10 in that the openable portion, delimited by the weakening
~:~ line, is pressed into the package, whereupon it may be torn
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off. This type of opening arrangement is customary in
packing containers e.g. for washing powders or flakes.
In packing containers e.g. for liquid contents the
opening arrangement described is not suitable. In packages
for liquid contents other solutions have therefore been
tried and a common one among these consists in providing
the packing container wall with a punched-out hole which
is covered by a tear-off tearing strip. However, this
opening arrangement is both expensive and more complicated
and moreover provides inferior impermeability to liquid
and gas which is a disadvantage in particular in the case
of sensitive foodstuffs.
A desirable solution consists therefore in modi~ying
the firstmentioned opening arrangement in such a manner that
the openable portion of the packing container wall can be
opened without having to be pressed into the packing con-
tainer and without the risk of splashing or spilling. This
modification can take the form of the opening arrangement
being provided with a tearing thread applied along the
weakening line, one end of which is accessible from the
outside of the package and by means of which the connection
of the openable part of the wall with the remaining packing
container wall can be broken. An opening arrangement com-
prising a tearing thread of this type functions very well
but will be somewhat complicated to manufacture, since the
application with sufficient accuracy of the tearing thread
is time-consuming and difficult, especially when the tear-
ing thread is to be applied along a curved opening indica-
tion line. In the mechanical, rapid manufacture of packing
containers from a moving material web therefore it has not
been possible up to now to apply the tearing thread with
sufficient accuracy.
It is an object of the present invention to pro-
vide an opening arrangement for packing containers which
is not subject to the abovementioned disadvantages.
It is a further object of the present invention to
provide an opening arrangement which is simple and fairly
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inexpensive and which moreover is easily openable.
It is a further object of the present invention to
provide an opening arrangement with a tearing thread which is
easy to apply also in the rapid, automatic manufacture of
packing containers, especially from moving material webs.
These objects have been achieved in accordance with
the invention in that an opening arrangement for packing
containers of the type wherein a part of the wall of the
packing container which is openable by means of a tearing
1~ thread is delimited by an opening indication line, is given
the characteristic that the opening indication line is
curved or arched, that the tearing thread extends substan-
tially rectilinearly between two points of the opening in-
dication line, and that the tearing thread is firmly at-
tached to the packing container wall at least at one of thesaid points. Owing to the tearlng thread being applied rec-
tilinearly in such a manner that it coincides only in two
points with the opening indication line, the application is
appreciably facilitated without the openability being im-
paired, since the tearing thread, once the tearing has pro-
perly started, will follow the weakened opening indication
line in the material.
An embodiment of the opening arrangement in accord-
ance with the invention has been g~ven the fuxther charac-
teristic that the tearing thread in packing containers whichare manufactured from weblike material runs parallel with
the direction of the web.
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac-
teristic that the tearing thread is fixed in a detachablemanner to the surface layer of the packing container wall
facing towards the inside of the package.
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac-
teristic that the opening indication line constitutes asealing line between two wall parts forming the packing con-
tainer.
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A further embodiment of the arrangement ln accord-
ance with the invention has been given the further charac-
teristic that the one end of the tearing thread extends
through the opening indication line and is located outside
the packing container.
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac- -
teristic that the end of the tearing thread extending out-
side the packing container is connected to a part of the
packing container material in the shape of a tearing tab~
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac-
teristic that the front end of the tearing thread located
outside the packing container meets the opening indication
line in an obtuse angle.
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac-
teristic that the openable part of the wall of the packing
container i5 in the form of a turn-up lid which is pivotable
about a straight line which extends between the end points of
the opening indication line and delimits the openàble lid part
from an adj~ining part of the packing container wall.
A further embodiment of the arrangement in accord-
ance with the invention has been given the further charac-
teristic that the said line coincides with the straight linealong which the tearing thread is detachably fixed to the
packing container wall.
The arrangement in accordance with the invention
will be described in more detail in the following with
special reference to the enclosed drawings which schemati-
cally show a preferxed embodiment of the arrangement in
accordance with the invention as provided in a known type
of packing container.
Figure 1 shows a packing container with an opening
arrangement in accordance with the invention before the
opening.
Figure 2 shows the packing container in accordance
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with figure 1 after the opening.
Figure 3 shows the successive phases in the manu-
facture of a packing container in accordance with figure 1.
The packing container shown in figure 1 is substan-
tially of the same type as that described thoroughly inSwedish patent no. 330.505, to which reference is made.
The packing container is made of a laminated all-plastic
material which comprises an inside layer of foamed plastic
material, e.g. polystyrene, which is covered on both sides
by homogeneous layers of the same material. The central
foamed carrier layer has a thickness of approx. 0,8 mm,
whilst the two homogeneous outer layers have a thickness
of only 0,1 mm. The com~ination of a relatively thick,
central foamed layer and homogeneous surface layers im-
parts to the material a good rigidity and makes it liquid-
tight at the same time. Through the choice of a thermo-
plastic material it becomes possible in a simple manner to
heat-seal the packing container.
As will be evident from the drawing, the packing
container is made of two parts, namely a semi-circular
or U-shaped curved casing part 1 and a back part 2, the
upper and lower end parts of which form the top part 3
and bottom part 4 of the packing container. The casing
part 1 and back part 2 are joined to one another by means
of a heat seal 5 extending around the whole edge surface
of the casing part. The outer end of the top part 3 re-
mote from the central portion 2' of the back part 2 has
the shape of an openable lid 6, the boundary line of
which against the remainder of the top part 3 coincides
with a tearing thread 7 which is situated in the lower
surface of the top part facing towards the inside of the
package and runs substantially parallel with the folding
line between the central portion 2' of the back part and
the top part 3. The tearing thread 7 passes through the
seal 5 in the vicinity of its end points/ and the one
end of the tearing thread extends a little outside the
seal where it forms a gripping tab 8, wherein the tearing
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thread end is attached to a projecting portion of the top
part 3.
The tearing thread 7 extends substantially recti-
linearly between two points situated symmetrically on the
sealing line 5. The part of the seal 5 situated between
these points (which may be weakened compared with the re-
maining extent of the seal) serves as an opening indication
line 5' along which the seal is caused to break with the
help of the tearing thread 7 when the packing container is
to be opened. As mentioned prev'ously, one end of the
tearing thread 7 is attached to the opening tab 8, and the
opposite end of the tearing thread, where it meets the
opening indication line 5' is also durably attached to the
packing container material. The portion of the tearing
thread 7 situated between the said points of attachment is
either wholly free or it is also joined detachably to the
surface of the packing container wall facing the inside of
the package.
In figure 2 the packing container in accordance with
figure 1 is shown after its opening. The packing container
according to figure 2 is otherwise identical with that shown
in figure 1 and comprises a casing part 1, an elongated back
part 2, the end parts of which form the top part 3 and bottom
part 4. The lid part 6, located at the outer end of the top
part 3, is shown in open or turned-up state, the straight
line which extends between end points of the opening indica-
tion line 5', that is to say, the line along which the tear-
ing thread 7 is situated before the opening, serves as a
folding line or hinge. As can be seen from figure 2, after
the opening of the packing container, the tearing t~read 7
continues to be attached with its one end to the packing
container. At the opposite end or front end of the tearing
thread the opening tab 8 attached to the tearing thread
is apparent which has been torn off the top part 3 on
opening.
Figure 3 shows schematically the manufacture of a
packing container in accordance with figures 1 and 2. The
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casing part 1 and the back part 2 respectively of the
packing container are manufactured from two separate webs
which in the first place are mechanically processed and
formed each for itself to be subsequently combined and
attached to one another so as to form packing contalners.
The manufacturing process, which is also described in de-
tail in Swedish patent no. 330.505 will here only be de-
scribed schematically to facilitate understanding of the
invention.
The two material webs consist as mentioned pre-
viously of a laminated material comprising a central layer
of foamed plastic material which is covered on both sides
with homogeneous thermoplastic material. One of the webs,
that is to say, the web which is to form the back parts of
the packing containers, i5 appreciably wider than the
other web and is provided moreover in the vicinity of its
upper edge ~figure 3) with the tearing thread 7, which can
be joined detachably to the homogeneous plastic layer which
eventually will constitute the inside of the packing con-
tainer. During the successive feed through the packingmachine the packing material web is converted in that cer-
tain portions ~including parts of the tParing thread) are
punched out along these two edges so that a line of sub-
stantially U-shaped lugs or off-cuts located opposite one
another is formed along the two edges. The lugs or off-
cuts will subequently form the top and bottom parts of the
packing containers and are situated in pairs opposite one
another transversely over the material web and they are
connected via intermediate portions which correspond to
the actual back part 2' of the finished packing con-
tainer. The off-cuts, as mentioned previously, are sub-
stantially of U-shape and consist thus of a portion located
closest to the centre back part 2' which is delimited by
substantially parallel edge lines and an end portion which
is limited by a substantially semicircular edge line. In
the off-cut which is to form the top part of the packing
container the semicircular edge line is broken by a pro-
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jecting tearing ta~ 8, which extends unilaterally from theone side of the top part at even height with the tearing
thread 7 running across the top part. To ensure a firmer
attachment of the two end parts of the tearing thread to
the top part 3 the a~ea on the tearing tab 8 as well as
the area on the opposite end or back end of the tearing
thread 7 can be subjected to a warming up to softening
temperature and to a compression which ensures attachment
of the tearing thread ends to the material of the top part.
At the same time as the abo~ementioned conversion
of the one material web a mechanical processing of the
other material web, that IS to say, the material web which
is to form the casing parts 1 of the packing containers is
also taking place. This material web is narrower than the
material web forming the back parts and has a width which
corresponds to the width of the punched-out area which is
to form the actual back parts 2' of the packing container.
The curved casing parts 1 of the packing containers are now
formed in that the packing material web is warmed up to its
softening temperature, whereupon it is subjected to a mecha-
nical shaping process during which the material web with
the help of a shaping tool is pressed down into a series
of continuous U-shaped recesses. Thanks to the thermo-
plastic characteristics of the material this shaping pro-
cess can be done without any damage to the material andresults in the material web being converted to a line of
continuous U-shaped casing parts l.
After this preliminary forming of the two material
webs, they are made to run substantially parallel and are
then brought together successively in such a manner that
the end portions of the legs of the U-shaped casing parts
come to rest against the central portion of the wider
material web which is to constitute the actual back par~s 2'.
It is ensured that the casing parts are so placed opposite
the top and bottom parts 3 and 4 respectively that these
parts in a following folding-down operation end up in
correct position and seal up the open sides of the casing
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parts. After correct placing, a warming up of the material
surfaces which are to be joined together with top and bottom
parts 3 and 4 respectively takes place, whereupon the latter
are folded down so that they come to rest against the late-
ral edges of the casing part 1 where a heat sealing iscarried out in that the material parts are pressed together
for a brief instant and are allowed to cool. Thereafter,
the packing containers are filled with the help of a ~iller
pipe not shown on the drawing which, making use of the
flexibility of the material, extends into the continuous
line of packing containers via the interspace between the
back parts 2 and the end portions of the legs of the casing
parts 1. The filling, like the whole of the manufacturing
process, occurs whilst the material webs are in continuous
movement, and simultaneously with a packing container having
been filled to the required extent it is also being moved
past the end of the ~iller pipe for the pack part to be
pressed against and sealed to the leg end of the casing
part, so that the packing container will now be fully closed.
This continuous line o~ filled and closed packing containers
is then divided whilst continuing its travel throuyh the
packing machine into individual packing containers, by
means of a cutter, not shown, which by transverse cuts
separates the still coherent packing containers from one
2~ another, whereupon the packing containers are ready.
When the packing containers are manufactured from
the packing laminate mentioned earlier consisting of a
central layer of foamed material, e.g. polystyrene, which
is covered on both sides with thin homogeneous polystyrene
layers, it is suitable for use as a tearing thread a cotton
thread which is impregnated with an acrylic polymer. The
thread should have a diameter of approx. 0,5 mm. As mentioned
earlier~ the two end parts of the thread are attached to the
packing container material in that the portions which are to
be joined are heated to the softening temperature of the
material (approx. 235C), whereupon the areas are allowed
to cool under compression so that a heat-sealing takes place.
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The part of the tearing thread located between these por-
tions may either extend freely along the inner surface of
the packing material or be joined detachably to the same,
e.g. by spot heat-sealing or hy a non-permanent sealing
which can be achieved by carrying out the heat-sealing at
a somewhat lower temperature and/or pressure.
Naturally, different materials or combinations of
materials are conceivable for the layers combined in the
packing laminate, bearing in mind a number of different
factors, e.g. the contents for which the package is intended,
the durability of the package, costs etc. The manner of rea-
lization of the tearing thread too may vary in respect of
shape as well as of material and it is conceivable e.g. to
give the tearing thread the shape of a relatively flat and
wide band. It is also possible to attach the thread ends to
the packing material with the help of an additional material,
e.g. a so-called hot-melt~ It is important, however, that
the tearing thread should be placed so that it extends sub-
stantially rectilinearly between the two points of attachment
on the edge lines of the lid part and furthermore that the
tearing thread extends parallel with the direction of the
web which appreciably facilitates the application. It is,
of course, important that the end of the tearing thread
should extend outside the packing container and it has been
found appropriate to join in the manner described above the
end of the tearing thread to a part of the packing container
material shaped as a tearing tab 8, since this appreciably
facilitates the opening of the package.
When the packing container is to be opened, the pro-
jecting tearing tab 8 is gripped and the tearing is startedupwards or possibly obliquely outwards across the rounded
edge lines of the openable lid part. The tearing tab will
then break and will be separated from the top part proper
of the packing container whilst the front end of the tearing
thread 7 connected to the tearing tab 8 commences to run
along and to cut through the seal between the top part 3 and
the casing part 1 serving as an opening indication line 5'.
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Slnce the end of the tearing thread 7 located outside the
packing container, owing to the rounded-off outer end of the
top part meets the opening indication line 5' at an oblique
angle (the angLe between the projecting front end of the
tearing thread and the opening indication line is obtuse
and preferably amounts to between 120 and 150, which value
has proved to give a safe control to allow a safe guiding
of the thread), the thread will run in the right direction
along the sealing line on opening. The tearing thread 7,
if it is at all attached to the inside of the packing mate-
rial, will then successively come loose and run along the
whole opening indicati~n line 5' until it is connected to
the packing container only by its back end. Owing to the
relatively great strength of the packing material compared
with the strength of the opening indication line 5, the
tearing thread runs without difficulty along the opening
indication line. This is also helped of course by the
fairly slight attachment of the major part of the thread
and the fact that the inside of the packing con~ainer mate-
rial is uniform and smooth, so that there is no risk ofthe thread running along a straight line towards its back
end.
When the seal along the opening indication line 5 has
been wholly broken by the thread 7, the front portion of the
top part serving as a lid 6 can be folded upwards so that an
opening is produced th~ough which the contents can be emptied
out. Thanks to the rounded shape of the casing part the
packing container is given excep~ional pouring properties and
even relatively sluggishly running, highly viscous contents
can be poured out in a well converging jet without after-
drip.
Since the packing container material owing to its
laminated and relatively thick build-up presents a certain
resistance to bending, which can make the opening of the
lid part 6 somewhat difficult, it may be advantageous in
certain cases if the tearing thread 7 during the manufac-
ture of the package i5 joined to the inner surface layer
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of the packing material by a heat-seal, since this results
in a certain weakening of the inner layer along the straight
line between the end points of the opening indication line
along which the tearing thread is fixed. This weakening of
the inner layer of the packing material facilitates the
folding up of the lid part and helps to make it possible
moreover to keep the lid part 6 in open position without -
having to retain it in this position by hand.
With certain types of tearing thread there may be
a risk of the tearing thread acting as a capillary tube and
conducting contents through the seal and out to the end of
the tearing thread located outside the packing container.
This risk can, of course, be overcome in most cases by
giving the tearing thread a suitable design or impregnation,
but in order to obtain absolute safety it is also possible
to place the thread underneath the surface layer of the
packing laminate, that is to say, between the surface layer
and the carrier layer. Since in such cases the thread is
applied to the carrier layer before the surface layer, the
thread will be partly embedded in the surface layer when
the surface layer is extruded and pressed to the carrier
layer, so that its function on opening of the packing con-
tainer will not be jeopardized. Such a placing of the tear-
ing thread has proved to work excellently together with e.g.
the said type of laminate comprising carrier layers of plas-
tic foam and surface layers of homogeneous polystyrene. By
using such a placing of the thread it was found that the
special sealing of the end parts of the tearing thread can
be wholly omitted, since the fixing of the tearing thread in
the material will be sufficiently strong in order to prevent
the tearing thread from being pulled loose in longitudinal
direction when the opening procedure is initiated.
To prevent the tearing tab 8 from suffering damage
or causing a premature opening of the package catching and
3S being pulled up during the handling of the packing container,
it is possible to fold the tearing tab downwards so that it
lies against the outer surface of the casing part 1 and to
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fix it there with the help of an easily detachable seal.
This does not make the opening any more difficult, but pro- -
vides good safety against inadvertent opening.
Although the opening arrangement in accordance with
S the invention has been described in the foregoing in direct
connection with a certain type of packing container, it is
o~ course also possible to utilize the opening arrangement
with other types of packing containers which e.g. may have
a wholly different shape or be manufactured from a different
material, be provided with conventional tearing indication
lines in the form of weakening perforations or differ in some
other manner from the preferred combination of packing con-
tainer and opening arrangement shown. What matters here is
only that the opening arrangement should be as specified by
the invention, that it to say, that the tearing thread should
extend substantially rectilinearly between two points on a
non-rectilinear opening indication line and be firmly attached
to the packing container wall at least at one of these points.
As a result of the design in accordance with the invention,
important advantages have been obtained when packing con-
tainers, e.g. of the type de,scribed, are to be manufactured
automatically, which previously has not been possible. By
placing the tearing thread so that its dixection coincides
with the direction of the web, the tearing thread of unbroken
length can be applied to the pack~ng container material at a
very high ~ate.
Finally the opening arrangement in accordance with the
invention will be very economical, since apart from the actual
tearing thread no extra material is re~uired. The tearing tab,
as shown in the example described, can often be made of surplus
material which otherwise would not ~e used.
