Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~07~7447
This invention relates to self-supporting containers,
that is to say containers which maintain their shap~
independently of the contents.
- Boxes and cartons are typical examples of self-
supporting containers, whereas bags are generally not self-
supporting. The shape of a bag usually varies according to the
size, shape and general characteristics of the contents.
Accordingly, goods which are packed in bags are less convenient
to handle and store, and frequently do not present such a
pleasant external appearance. On the other hand, bags are very
easy to make in large numbers, and can be sent out in a -
completely flat condition, whereas boxes and cartons generally
take longer to make, usually requiring a separate erection
operation, and requiring special design features to enable them
to be sent out in the flat condition. Moreover, bags can
relatively easily be made sift-proof, whereas this is much more
difficult for cartons and boxes.
In accordance with one broad aspect, the invention
relates to a method of making a self-supporting container which
comprises laminating two or more layers of flexible sheet
material by means of an intermediate settable adhesive
composition, forming the laminate into a collapsed container by
a cutting and folding process before the adhesive has set, and
then allowing or causing the adhesive to set to form an
erectable container with stiff walls.
Preferably, the laminate is made into a collapsed
container by a cutting and folding process before the adhesive
has set, so that when filled the container will assume a -
rectangular configuration, resembling a carton. Suitably, the
laminate material is formed into a bag, for example by
conventional bag-making procedures, preferably a
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block-bottom or self-opening satchel (S.O.S.) type of bag.
In this latter embodiment, bottom flaps of the bag may be
folded over and adhered in an overlapped condition, and are
preferably secured in this condition by releasable retaining
means, such as a peelable adhesive or a peelable self-
adhesive patch so that the container can be opened from that
end by cutting off a corner of one flap, the other end of
the container being permanently sealed when the contents are
enclosed. The other end may be closed by heat sealing
together opposed surfaces of the container to form an end
fin, and then folding the fin over and sealing it to the ;
rectangular end of the container.
In a second aspect the present invention provides a
self-supporting container made by the method of the invention.
The inner layer of the laminate may be made of a
barrier material, for example a foil or a plastics film, or
be a laminate which includes such a material. Suitably, the ~-
~container is made from a laminate o~ two layers of paper,
either or both of which may have a barrier layer on its
surface remote from the other. The layers may be adhered
together by means of a starch based adhesive, which allows
the laminate to be cut and creased while the adhesive is
still wet, but dries to produce a stiff laminate. The
laminating adhesive may itself include a component which
imparts barrier properties to the laminate.
In order that the invention may be more clearly
understood, one embodiment will now be described with
reference to the accompanying drawings, wherein:
Fig. 1 shows a perspective view of an S.O.S. bag in
30 the flat condition before filling, --
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~077447
Fig. 2 shows a perspective view of the filled and
closed bag, and
Fig. 3 shows a perspective view of the S.O.S. end of
the bag which has been opened for access to the contents.
Referring to the drawings; two webs of paper are
laminated by an application of a heavy starch based adhesive,
and the laminate is cut and creased in conventional manner to
form an S.O.S. bag as shown in Fig. 1. The bag has front and
back panels 10, side panels 12 which are pleated at 14, and a -
square bottom end 16 in which opposite triangular flaps 18,20
are folded over and secured in an overlap condition by the
application of a pressure-sensitive adhesive patch 22. When
the starch based a~hesive has set the laminate material is
stiff, so that the bag will readily retain a carton-like
rectangular appearance when it is opened for filling. - ~-
Fig. 2 shows the bag after it has been filled, and
the open end closed by sealing together opposed surfaces of
the material at the mouth of the bag to form a fin 24. A bag
~ nd 29
closing machine also creases the mouth of the bag at 2~ so
that the fin can be fold0d over as indicated by the arrow A
to lie flat against a rectangular end of the bag, and it can
be adhered in this position, so that the bag can then be
inverted and stood on that end. The S.O.S. end thus becomes
the top of the bag and preprinting of the bag material can
be arranged accordingly.
When it is desired to open the bag, the patch 22 is
peeled away, and the corner of one of the flats 18,20 is cut
off, as shown at 28 ~n Fig. 3, so that the contents can be
poured out. The bag can then be reclosed by folding the
flaps 18,20 back, as shown by the arrows B, and inserting
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1077447
the apex of the uncut flap into the opening formed by the cut
28 on the other flap.
m e interply adhesive material may include barrier
materials to suit the particular commodities or the inner
layer of the bag may carry a barrier layer such as a plastics
film or a~luminium foil on its inner surface. The adhesive
material may be,for example, a thermosetting resin. In such
an embodiment, the resin could be cured by heat treatment, or
other treatment such as irradiation, during or after filling.
The outer surface of the outer layer of the bag may have a
barrier layer to prevent ingress of moisture and other
contaminants.
It has been found that filled bags of the present
invention retain their rectangular carton-like appearance,
and can be stacked several bags high without collapse.
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