Note: Descriptions are shown in the official language in which they were submitted.
- l~lZ33~
The present invention relates to a plastic bag with a
filling valve and a gas-permeable fine-material-filterin~a layer
to permit gas to escape from the interior of the bag to the exterior.
Plastics bags of this type with a filling valve, are known.
When stacking these known plastic bags after filling,problems may
arise. In many cases pulverized material which has to be packed with
much air in a bag of this type, tends to escape with enclosed air and
to adhere to the outside of the bag. This material will then function
as a sliding means, thus hampering the stability of stacked plastic
bags.
It has further been observed that when air escapes from
stacked bags,this does not proceed perfectly so that in case of
somewhat leaking valves or leaking parts of the bag, not only said
air escapes, but also a small quantity of the pulverized or powdered
product. The latter implies also a great number of undesired sliding
points in a stack of bags.
This sliding will furthermore be increased in that the
pulverized material, escaping from the bag, adheres to the outside
of plastic bags owing to electrostatic charges.
Efforts have been made to solve the abovementioned problems
by giving the bags a rough outside but this roughening did not produce
the desired results. Consequently pulverized materials are therefore
presently packed in paper bags exclusively.
The said paper bags are, however, not moisture-resistant
and may be easily damaged during a long distance transport so that
the packed substances will get lost.
It has also been proposed to provide the whole wall of a
plastic bag with small pores which only permit an escape of air, but
in practice it has appeared that the said pores are insufficient.
Not only will the air escape too slowly, but the pulverized material
will also escape through the pores as yet or will close them off
completely~
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11~33~
f~
The pre~ent invention ~imY to provid~ a
pl~tic bag ~hich the ~bove-mentioned di~ndvantnges nre
~llevi~ted.
In nccordance with the pre~ent invention there
~ 9 provided a plasticq bag having ~t respective corners
of one end of the bag, a filling entry throu~h which th~
bag can be filled and a ga~ exit through which gas cnn
~scape from the interior of the bag, the gas exit
comprisin~ ~ pocket formed of a gas perme~ble materi~l
which extends into the bag between an end wall of the bag
nnd an inturned corner-flap of the bag, the exterior
of the pocket being ~ecured to said end wall and c~rner
flap.
` The pocket in addition to providing an exit
for gas from the bag al~o pro~ides a mean~ by which the
bag can be easily removed from the fillin~ nozzle ~fter
the ba~ has been filled ~nd for thi~ reason advant~geously
the pocket interior i~ freely accessible from the exterior
of the bag whereby ~he bag may be seized by puttin~ a hand
into the pocket.
~ he ga-q permeable material advantageously
may compri~e non-woven thermopla~tics material for
example polyethylene fibre~ or ~ore preferably polyester
fibreq.
Advantageou~ly the ~a~ permeable material
of the pocket comprise~ a layer of material which permits
permeation of gas therethrough in the plane of the layer
~nd perpendicularly thereto.
Furthermore, the exterior o~ the pocket may
be~secured to the end wall and corner flap of the bagby
being he~t ~ealed thereto, or by means of ~n adhesive.
In order that the invention ~ay be well
understood an embodiment thereof will now be de~cribed
with reference to the ~ccompanying drawings, in which:
- Fig. 1 schematically shows part of a plastic bag with a filling
valve in accordance with the invention;
- Fig. 2 schematically shows part of a plastic bag comprising a
gas-permeable layer located opposite the filling valve, in the shape of
a non_woven pocket;
- Fig. 3 shows a top view of a bottom of a bag provided with a
filling valve and a gas-permeable pocket in accordance with ~ig. 1 and 2,
- Fig. 4 shows a cross section through a filling valve and a
gas-permeable layer in the bag of Fig. 3 .
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~lZ3392
Fig. 1 shows ~ plastic bag 1 comprising a front bag foil layer
and a rear bag foil layer ~orming togeth~r a tubular foil of e.g. poly-
ethylene foil material.
Bag 1 is provided with a bottom 2 formed by a first bottom
flap ~ and a second bottom flap 4 which are interconnected by an adhesive
connection or a welding joint 5.
The first and second bottom flap 3 and ~ present a bottom flap
end edge 8 and ~.
When forming the bottom, first and second corner flaps 11 and
12 are simultaneously formed. The first corner flap 11 is provided with
a first corner flcp edge 14 being located within the bag. The second
corner flap 12 is provided with a second corner end edge 13.
After having formed the corner flaps ~1 and 12 a plastic valve
tube 6 is positioned onto the first corner flap 11. Prefer~bly an inner
end part 16 is folded backwards towards the protruding end 17 of the
valve tube 6, and this part 16 will be fixed to the first corner flap 11
and a bottom covering foil layer~21.
The valve tube 6 will constitute a ~illing valve 1O located
within the bag and extending in the bag farther than the corner flap
end edge 14 of the second corner flap 12.
The free end edge 17 of the filling valve tube o will protrude
outside the interior of the bag. By means of adhesive connections or
heatseals 19 and 20 the valve tvbe 6 is connected with the corner flap 11
and with a bottom covering foil layer 21 which is fixed along the folded
back bottom flaps 3 an`d 4. Upon the second corner flap 12 ~ pocket 22
of gas-permeable material is fixed of a length such, that same extends
to beyond the inner end edge 13 of the second corner flap 12 inside the
bag.
In the vicinity of it~ free outer edge 23 the pocket 22 is
affixad to the bottom foil 21 covering the bottom flaps 3 and 4 being
folded toward each other and the parts of the second corner flap 12
located directly therebelow, by means of an adhesive or a heatseal~
It will be clear that the fine-materials-filtering gas-permeable
pocket 22 permits a gas or air as used for filling and now being enclosed
in the bag to escape, as the interior of the bag is now connected with
the exterior thrcugh the gas-permeable pocket 22. This gas-permeable
pocket 22 comprises layers 22a and 22b, the edges of which are inter-
connected or integral with each other, thus forming said gas-permeable
pocket 22.
- 11233~2
After having filled the bag by means of a filling machine,
during which period the bag suspends from the filling machine through
the filling valve 6, the bag can be easily removed from the filling
machine, as by putting a hand in the pocket 22, the plastic bag, which
is very smooth, may be easily seized and re~oved from the filling machine.
~ or that purpose the mouth 26 of the pocket 22 is opened,
~h~reafter a hand can be put into the pocket 22 until same reaches the
pocket bottom 15 of the pocket 22. As can be seen, the pocket bottom 15
extends within the bag to beyond the edge 14 of the second corner flap 12.
The second corner flap 12 and the bottom covering foil 21 are unable to
contact each other 60 that an optimum removal of gas or air is ensured.
The pocket bottom 15 forms the air,permeable connection between the two
layers ~2a, 22b.
As can be seen, the adhesive strip parts or heatseals ~4 and
25 connect the layer 22a of the pocket with the inner side of the in-
wardly folded parts of the bottom flaps 24a, 24b and with the covering
foil 21 and layer 22b with the corner flap 12.
For filling the bag,mouth 10 of the filling valve 6 is opened.
Fig. 3 shows that the adhesive strip parts or heat seals 2na and 20b are
disposed between the tubular valve foil 6 and the inside of the inwardly
folded parts of the bottom flaps 3 and 4. So as to avoid loose parts of
the covering bottom layer 21~the end region 27 of the covering layer 21
is completely connected to the valve tube 6 along its whole width in,a
flatte m d state.
If desired, the covering layer 21 can be omitted and the
bottom can be formed by providing the tubular bag foil with incisions
and folding the bottom flaps, as described in British Patent Specification
1 07~ 856.
It should be noted that the bags according to the invention
are very advantageous in that the strength of none of the bag walls is
impaired by using the gas-permeable layer. This is mainly due to the fact
that the gas-permeable l~yer is covered by the bottom parts of the bag.
~ ~ . .~ .
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- 1~233~2
Those skilled in the art will appreciate that
further embodiments ma~ exist falling within the scope
of the present invention, even though departin~ from the
preferred embodiment described above.
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