SAC POUR PRODUITS LIQUIDES PRODUISANT DES GAZ, PARTICULIEREMENT LA LEVURE

BAG FOR THE CONTAINING OF LIQUID PRODUCTS EMANATING GAS, IN PARTICULAR YEAST

Abrégé français

Il est décrit un sac pour produits liquides produisant des gaz, particulièrement la levure, du type à double paroi, comprenant deux faces opposées (2) reliées les unes aux autres le long dune ligne de thermoscellage de périmètre (3) et un bec verseur (7) pour remplir ou distribuer le produit liquide placé sur lune de ces faces (2), la double paroi du sac comprenant un film interne à base de polyéthylène (5) ayant une perméabilité élevée et un film extérieur de renforcement (6), ledit film extérieur (6) étant constitué dun non-tissé à base de polyéthylène.

Abrégé anglais

Bag for containing liquid products which produce gas, in particular yeast, of
the double
wall type, comprising two opposite faces (2) joined one to the other along a
perimeter
heat-sealing line (3) and a spout (7) for filling/delivering the liquid
product placed on one
of these faces (2), the double wall of the bag comprising a polyethylene-based
inner film
(5) with high permeability and a reinforcing outer film (6), wherein said
outer film (6) is
made of a polyethylene-based nonwoven fabric.

Revendications

6
CLAIMS
1. Bag for containing alimentary liquid products which produce gas, in
particular yeast, of
the double wall type, comprising two opposite faces joined one to the other
along a
perimeter heat-sealing line and a spout for filling/delivering the liquid
product placed on
one of these faces, the double wall of the bag comprising a polyethylene-based
inner film
with high permeability and a reinforcing outer film, the outer film having
micro holes
over the entire surface and wrinkles preventing such an adherence to the inner
film that
would clog the micro holes, said outer film being made of a polyethylene-based
nonwoven fabric.
2. Bag according to claim 1, wherein said nonwoven fabric is a mixture of
polypropylene
and polyethylene (PP/PE).
3. Bag according to claim 2, wherein said nonwoven fabric of the outer film
has a weight
of 60-85 g/m2.
4. Bag according to claim 1, wherein said inner film is a coextruded LLDPE of
30 µm and
28 g/m2.

Description

1
BAG FOR THE CONTAINING OF LIQUID PRODUCTS EMANATING GAS, IN
PARTICULAR YEAST
DESCRIPTION
The object of the present invention is a bag for the containing of liquid
products which
emanate gas, in particular yeasts for bread making.
In the following description specific reference will be made to yeast, but it
is to be
understood that the invention can be applied to any liquid or paste product
which during
storage emanates gas.
Yeast, in the phase of production, is always in the liquid state and, for the
placing on the
market, in the majority of cases, is subsequently dehydrated in order to
transform it into
powder or into the form of solid cakes. In the phase of use the yeast has once
again to be
returned to the liquid form.
In recent times there has been the tendency to produce and package the yeast
directly in
liquid form which is advantageous from practical and economic standpoints in
that the
phases of transformation from the liquid state to the solid state during
production and vice
versa during use are eliminated.
The problem in the storage of the liquid yeast is that it emanates a
considerable quantity
of gas, in particular CO2, up to 1/3 litres a day for a package of 10/20
litres.
Bags are therefore necessary which on the one hand are highly permeable to the
gases and
on the other hand have adequate toughness for sustaining the weight of the
content, these
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2
bags normally having a capacity of 10/20 litres.
In order to meet these needs "double wall" bags have therefore been proposed,
i.e. having
a polyethylene-based inner film highly permeable to CO2, with very thin
thickness (30-50
pm) and therefore with little mechanical strength, and an outer film
constituted by a
nylon-based laminate, with thickness of 80-150 lam, suitable for conferring
the necessary
mechanical strength to the bag.
The outer film, which is not permeable, has a plurality of small holes to
allow the release
of the gases which permeate through the inner film.
The bag shaped in this way is placed inside a cardboard box in such a way as
to constitute
a so-called bag-in-box packaging which can easily be manipulated.
The bags of the aforementioned type have not proved to be satisfactory in that
despite the
providing of the perforated outer film an unsatisfactory release of the gases
which tend to
inflate the bag has been noted.
This is due to the fact that when the bag filled with liquid yeast is inserted
in the
cardboard box it adapts to the box, causing a pressure contact between the
outer surface of
the bag and the inner walls of the box, apart from the head space of the bag
which remains
clear.
This pressure contact causes a strong adherence between the inner and outer
plastic films
of the bag, practically clogging the holes provided in the outer film and
preventing
therefore the release of the gases, which tend to accumulate in the upper part
of the bag,
where they have difficulty in exiting due to the small perforated surface of
the outer film
not in contact with the inner wall of the containing box.
The object of the invention is that of eliminating the aforesaid disadvantages
of the prior
art.

3
More particularly an object of the invention is that of providing a bag for
liquid yeasts
which allows a complete and rapid degassing of the product contained therein.
Another object of the present invention is that of providing such a bag which
is simple
and economical to manufacture.
Substantially the bag according to the invention, of the so-called double wall
type,
comprises a polyethylene-based inner film with high permeability and a
reinforcing outer
film, wherein the outer film is a nonwoven fabric of polyethylene-based
fibres, so as to be
to sealable to the inner film.
Conveniently the fibres of the nonwoven fabric of the outer film are
constituted by a
mixture of polypropylene and polyethylene (PP/PE), with a weight of 60-85
g/m2.
Further features of the invention will be made clearer by the following
detailed
description, referred to one of its embodiments purely by way of a non-
limiting example
illustrated in the accompanying drawings, in which:
Figure 1 is a schematic plan view of the bag according to the invention;
Figure 2 is an enlarged section view taken along line II-II of Figure 1;
Figure 3 is a schematic perspective view of the bag of Figure 1.
Referring to these drawings, the bag according to the invention, for the
containing of
liquid products which emanate gas, in particular yeast, has been denoted by
reference
numeral 1.
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4
It comprises two opposite faces 2, joined by means of perimeter heat sealing
3, which
runs parallel to its outer edge 4.
In the accompanying drawings the bag 1 has been illustrated rectangular in
shape, which
is the simplest to make, but it is clear that it can take on any other shape.
The bag 1 is of the so-called double wall type, in the sense that each of its
two opposite
faces 2 comprises two films, an inner one 5 and an outer one 6, separated one
from the
other and joined only at said perimeter heat-sealing line 3.
On one of the two faces 2 of the bag 1 a spout 7 for filling/delivering of the
product is
applied, having a circular flange 8 sealed internally to the corresponding
face 2, while the
spout 7 projects through a hole formed in this face, and is closed by a cap 9.
The inner film 5 of the double wall of the bag is with high permeability to
gases, in
particular to CO2 which is produced in a large quantity by the yeast contained
in the bag,
> 50 1/m2day atm. It has a base of polyethylene, for example a coextruded
LLDPE and has
a very thin thickness (around 30 gm) and a weight of 28 g/m2 in order to be
able to obtain
the aforesaid high values of permeability.
Such a film would alone be very fragile and therefore subject to easy tearing.
Therefore the outer film 6 is assigned the task of conferring toughness to the
bag and
avoiding easy breaking.
This outer film 6, according to the invention, is a nonwoven fabric of fibres
constituted by
a PP/PE mixture of 60-185 g/m2.
The presence of polyethylene in the mixture constituting the fibres of the
nonwoven fabric
allows the performance of the perimeter heat sealing 3 to the inner film 5, as
well as the
heat sealing of the base 8 of the spout 7.

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The manufacture of the outer film 6 in PP/PE nonwoven fabric allows the
elimination of
the disadvantages due to the adherence between the inner and outer films when
the bag 1
is inserted in a containing box (bag-in-box) normally in cardboard.
5 In fact the greater wrinkling of the nonwoven fabric according to the
invention, with
respect to the perforated plastic film of the prior art, prevents the
adherence between the
films and allows easy release of the gas, in particular CO2, through the
nonwoven fabric
of the outer film 6, which has micro holes over the entire surface.
to From what has been disclosed the advantages appear clear of the
invention which allows,
with simple and economical means, the complete and rapid release of the CO2
gas
produced by the liquid contained in the bag I.
Naturally the invention is not limited to the particular embodiment previously
described
and illustrated in the accompanying drawings, but instead numerous detail
changes can be
made thereto, within reach of the person skilled in the art, without thereby
departing from
the scope of the same invention as defined in the annexed claims.

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