Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02593841 2007-07-05
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Packaging Pouch
The invention relates to a pouch for packaging purposes made from a flexible
film-type material and having at least one sealing zone arranged along an edge
of the pouch and an outer sealing seam as a permanent means of closure.
Goods required for daily use are often packaged in pouches. A classic pouch-
system is the free-standing pouch or the "Doy-Pack" type of pouch. Depending
on the contents and the requirements, the layers of material may be two to
four
main layers.
Typical layer arrangements in packaging laminates for the manufacture of
pouches for liquid, liquid/particulate-solid and pasty type contents having a
long
shelf-life of more than thirty days are e.g.
PET / aluminium / oPA / PE (or PP)
PET / vacuum coated barriers / oPA / PE (or PP)
PET / vacuum coated barriers / PET / PE (or PP)
PET / PE :EVOH:PE (or PP:EVOH:PP)
The combination of different layers produces the desired properties. PET
(polyethylene-terephthalate) is thermal resistant, produces a shiny surface
and
can be readily printed on, oPA (oriented polyamide) produces a high resistance
to penetration and resistance to failure due to bending, an aluminium foil,
vacuum coating with SiO,, or a layer of EVOH (ethyl-vinyl-alcohol) as barrier
layer increases the resistance to the passage of water vapour, oxygen and
other gases as well as undesirably aromas. The thickness of the various
individual layers varies, depending on the specific application. Typical film
thicknesses are: PET 12 pm, aluminium 8 - 12 pm, oPA 12 - 15 pm, PE and
PP 50 - 150 pm. The films or foils are typically bonded together by means of
polyurethane adhesives.
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Apart from the different properties, the combination of layers also produces
the
required toughness at the sealing joint, which gives the finished pouch its
shape. This prevents the pouch from bursting open if dropped, which would
make the contents unusable.
The production of the above mentioned arrangement of layers is relatively
complex. There is therefore the desire to have layers that are easier to manu-
facture, that are cost-favourable and to have fewer layers e.g. laminates
having
only two main layers. The materials employed must combine different
properties, in particular however prevent the finished pouch from tearing open
along the sealing seam if dropped several times.
The object of the present invention is to improve the shock-absorbing capacity
of the sealing seam in a packaging pouch of the kind mentioned at the start.
That objective is achieved by way of the invention in that, in order to
increase
the shock-absorbing capacity, a region of the sealing zone bordering the
interior
of the pouch exhibits lower bond strength than the bond strength of the outer
part of the sealing seam.
The essence of the invention lies in the placement of an additional sealing
area
which, when a pouch is dropped, absorbs the energy acting on the sealing zone
of the pouch or reduces this to such an extent that the outer sealing seam is
not
impaired. A tear which, when a pouch is dropped, starts in the region of the
seam that precedes the outer sealing seam and has the lowest bond strength,
is arrested by plastic deformation taking up the kinetic energy running into
the
sealing zone i.e. before the tear reaches the outer sealing seam.
The region of the sealing seam bordering the interior of the pouch may e.g.
exhibit an inner sealing seam having lower bond strength than that of the
outer
sealing seam.
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The region of sealing zone bordering the interior of the pouch may also
exhibit a
plurality of sealing areas that are spaced apart and exhibit the same or lower
bond strength than that of the outer sealing seam. Thereby, the sealing areas
that are spaced apart may exhibit geometric figures that are surrounded on all
sides by seal-free regions or form a geometric pattern.
The sealing areas that are spaced apart from each other may also be strips
that
project from an inner edge of the outer seam, or strips that project from an
inner
edge of the outer sealing seam and are delimited by inward projecting seal-
free
regions.
The region of sealing zone bordering the inner part of the pouch and
exhibiting
lower bond strength than that of the outer sealing seam may extend the whole
length or may run only over one or more parts of the length of the outer
sealing
seam.
Further advantages, features and details of the invention are revealed in the
following description of preferred exemplified embodiments of the invention
and
with the aid of the drawing which shows schematically in
- Fig. I a side view of a free-standing pouch with outer and inner sealing
seam;
- Fig. 2 the side view of the free-standing pouch shown in Fig. 1, having
outer sealing seam and sealing areas that are spaced apart;
A packaging pouch 10 in the form of a free-standing pouch shown in Fig. 1
features a front wall 12, a rear wall 14 and a sealed on base 16. A
circumferential sealing seam 18 of elevated bond strength hermetically seals
an
inner volume 20 delimited by a front wall 12, rear wall 14 and base 16.
An inner sealing seam 22 having lower bond strength than that of the outer
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sealing seam 18 borders on one side to the region 20 for holding the contents
and on the other side to the inner edge 19 of the outer seam 18 and extends
over the whole length of the outer seam 18.
A tear arising when the pouch is dropped begins at the inner seam and is
arrested there due to the absorption of energy. The bond strength of the inner
seam 22 may e.g. be selected such that separation of the inner seam 22 takes
place by peeling.
As shown in Fig. 2, reduced bond strength at the inner side of the outer seam
18 may be achieved by the sealing in this region being achieved by a plurality
of
sealing areas that are separated from each other i.e. instead of by a seam
covering the whole area.
The sealing areas shown by way of example in a first version comprise
geometric elements e.g. triangles 24 which are surrounded by seal-free
regions.
In a second version shown here, the sealing areas are arranged spaced apart in
the form of strips 26 projecting out from the inner edge 19 of the outer seam
18
towards the interior 20 of the pouch.
In a third version shown here the sealing areas are in the form of strips 30
projecting from the inner edge of the outer seam 18 that are arranged spaced
apart and are delimited by seal-free regions 28.
