Note: Descriptions are shown in the official language in which they were submitted.
" ` 12795~3B
COMPOSITE BAND FOR LIDS FOR THERMOPLASTIC CONTAINERS AND METHOD,
DEVICE AND INSTALLATION FOR MANUFACTURING SUCH A COMPOSITE BAND.
___~a_ _____________________________________________________________
05 BACKGROUND OF THE INVENTION
The present invention relates to a composite band for
lids for thermoplastic containers having a flat and preferably
horizontal upper edge or rim, said composite band being of the type
comprising downward from the top: a first thin band in aluminum or
equivalent material, a thermo-adhesive film bonded to the lower
face of the first band, and a second band in thermoplastic material
adhering to the first band via said thermo-adhesive film and
adapted to be separated therefrom by peeling off, said second band
having, in each part corresponding to the position of each lid to
be subsequently cut out, at least one slit of curved configuration
defining a passage and the ends of which are either located closely
or coinciding.
DESCRIPTION OF THE PRIOR ART
This type of composite band is already known from French
Patent No. 81 06 557 (Publication No. 2 503 û36).
Given the fact that the first upper band may be removed
by being peeled off, the second band, which is normally
thermobonded in tight manner on the upper edge of the container,
and that the slit traverses perpendicularly the second band up to
the first band, tightness failures may occur along the separating
interface between the first and second bands, thus giving bacteria
uncontrolled access into the container by allowing them to follow
the said interface as far as the slit.
According to another solution proposed in French Patent
No. 83 13639 (Publication No. 2 551 031), a passage opening is made
in the second band in an area where a lid is provided, said opening
being covered over on one side by the first band bonded in peelable
manner to the upper face of the second band except where said
opening is provided, and on the other side, by a thermoplastic
1279S88
sealing off strip which is firmly i.e. non-removably bonded on the
one hand, to the lower faGe of the second band and, on the other
hand, where the opening into which it penetrates, is situated on
the lower face of the first band.
05 Although said thermoplastic strip is capable of
conferring to the lid the required tightness before the peeling off
of the first band, since it is tightly sealed to the edge of the
container and adheres firmly to the lower face of the second band,
it nevertheless comprises other disadvantages as regards the
production of the composite band and the uncovering of the passage
opening.
During the manufacture of the composite band, and in
particular during the step consisting in making the passage
openings in the second band, the stamped-in parts of the second
band are difficult to remove and delay the positioning of the first
band and of the thermoplastic strip. Moreover, said latter must be
sufficiently supple in order to penetrate into said passage opening
and to adhere firmly to the lower face of the first band. It is
generally found that the film or strip does not adhere to the first
band in the area of the edge of the passage opening.
When the passage opening is uncovered, namely when the
first band is peeled off from the second bonded band, via the
thermoplastic film on the edge of the container, said film is
stretched through the passage opening by the first band to which it
is bonded, and should tear off along the edge which is constituted
by the edge of the opening made in the second band. It has been
found that the film tears off uneasily and irregularly, so that
the passage opening, once uncovered, does not present a neat and
clean-cut outline.
It is the object of the present invention to overcome
these disadvantages by proposing a composite band of the
aforementioned type which enables the consumer to have a neat and
clean-cut opening and which can be manufactured in a simplified
manner.
~L27~S~38
OBJECT AND SUMMAR~ OF THE INVENTION
This object is reached according to the invention with a
composite band of the aforementioned type due to the fact that:
05 - the slit is defined on both sides by faces which are
very close together and perpendicular to the lower face of the
second band,
- the first band is bonded to the second band via two
thermo-adhesive films with different adhesive powers, the film with
high adhesive power being provided inside the area defined by the
slit and the film with low adhesive power being provided outside
that area, and
- a thermoplastic tightening or sealing film adheres
strongly to the entire lower face of the second band, inside as
well as outside the area defined by said slit.
According to these particular features, there is no
possibility for the thermoplastic film to stretch and said film is
cut cleanly in the spot where the edge formed by the lower face of
the second band and the vertical external face of the slit is
:~ 20 situated, said vertical external face constituting the edge of the
uncovered passage opening, when the first band has been peeled off.
Another advantage of this concept resides in the fact that the part
of the second band situated inside the area defined by the slit is
only removed at the moment when the passage opening is uncovered
and remains attached to the first band.
BRIEF DESCRI~lON OF THE DRAWINGS
The invention will be more readily understood on reading
the following description with reference to the accompanying
drawings, in which:
Figure 1 is a diagrammatical perspective view of a length
of a composite band with lids, equipped on its lower face with a
band for containers or with a protection band,
Figure 2 is a plan view of a container with a lid
according to the invention,
Figure 3 is an elevational view of a cross-section along
1;~79588
line III of Figure 2 showing a container with a lid according to
the invention,
Figure 4 is a view similar to that shown in Figure 3, but
with the lid having its passage opening uncovered,
05 Figure 5 is a diagrammatical plan view of the composite
band for lids, showing different configurations and dispositions of
the passage opening, the thermoplastic film being permanently
heat-bonded on the edges of the set of containers,
Figure 6 shows a vertical section of one of the
containers of Figure 5, taken along line VI-VI of said Figure, and
Figure 7 is a view of a detail A from Figure 6.
DES~RIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings, Figure 1 shows that the
composite lid band 1 comprises, downward from the top layer, a
first band or sheet 2 of aluminum or equivalent material which is
provided with a thermo-adhesive film 3, and a second band made of
thermoplastic material 4. Said thermo-adhesive film 3 or other
type of adhesive layer exerts a relatively low adhesive force on
the two bands 2 and 4 so that these can be peeled off one from the
other. In those areas of the composite band corresponding to lids
to be subsequently cut, or, to be precise, in those lid parts
situated above the openings of the containers, the second band 4
comprises, for each lid, slit 5 obtained preferably by localized
melting or punching of the thermoplastic material of the band 4
after the bonding thereof with band 2. Said slits 5 are defined by
faces 70, 71 perpendicular to the contacting faces of the band 4,
they follow a closed or nearly closed curve or loop and extend
from the lower face to the upper face of the second band 4, and
they can even be cut through the thermo-adhesive film and reach to
the lower face of the aluminum band 2. The distance between the
two parallel faces 70, 71 of slit 5 is very small so that even a
thin layer of thermoplastic material cannot penetrate therein, for
example, when said thermoplastic material is in a molten state.
Part 6 of the second band 4, which part 6 is situated
inside the zone defined by a slit 5, adheres very strongly to the
12~79~38
first band 2 by means of a layer of adhesive having a high adhesive
power 72 and part 7 of said band 4, which part 7 is situated
outside the area of part 6 defined i.e. surrounded by the slit 5,
is bonded to the first band 2, at least along a zone close to said
05 slit 5, in a tight but removable manner, thanks to the
thermo-adhesive film 3. Thus, the bonding achieved between bands 2
and 4, outside the area surrounded or defined by slit 5, is of such
a strength as to allow peeling of aluminum band 2 from
thermoplastic band 4, whereas within said area delimited by slit 5,
part 6 of the band 4 remains firmly bonded to the aluminum band 2
due to the action of the film or layer of adhesive 72 with high
adhering power.
The entire lower face of the second band 4 is firmly
bonded, either directly or through a layer of adhesive with high
adhering power 73, to a thermoplastic film 74, and this, in both
parts 6 and 7 of band 4, i.e. within as well as outside the area
defined by the outer face 71 of the slit 5, said area thereafter
` becoming an access or passage opening 15. The thermoplastic film
74 is designed to cover,in a tight manner, the slit 5 and to be
permanently and tightly bonded to the edge of the containers 9.
As described in French Patent No. 81 06557 (Publication
No. 2 551 031), the composite lid band 1 may be equipped with a
third band 8 which is either a protective band, or at the same time
a band called a container band, since it is from that band 8, which
in this case will need to be in thermoplastic material, that the
thermoplastic containers 9 will be formed by thermo-form, after
separation of the lid band 1, which containers 9 once filled with a
product, will be sealed off by means of said lid band 1.
Figures 2 to 4 illustrate a plan view and cross-sectional
views of a container 9 complete with a lid 10 produced from the
composite band 1. Said lid 10, of the same structure as composite
band 1, cùmprises, inside the opening zone 11 of the container 9,
the slit 5, and is heat-sealed on the flat edge rim 12 of said
container 9, so that the thermoplastic film 74 of the lid 10
adheres permanently and tightly to the material constituting the
127~38
edge 12. The operation consisting of heat-sealing the lid 10 is
performed in the conventional way. In order to facilitate the
start of the aluminum band or sheet 2 peeling off operation for
uncovering the access or passage opening 15, a zone tip (tiny area)
; 05 76 free of any thermo-adhesive film 3, is provided on the lower
face of said aluminum band 2, corresponding ~o a gripping corner 75
of the edge 12 of container 9, this permitting easy gripping of
aluminum sheet 2 and peeling off thereof at least until the access
opening 15, defined in the second band 4 by slit 5, is uncovered.
Given that part 6 of band 4, which part 6 is encircled or defined
by slit 5, is very strongly bonded both to the aluminum sheet and
to the thermoplastic sealing film 74, which in its turn is
thermo-sealed to the edge 12 of the container 9, the part of film
situated inside the area defined by outer face 71 of slit 5 is torn
along the edge formed at the intersection of said outer face 71
with the lower face of second band 4 and is removed with part 6 of
said second band 4, when said aluminum sheet 2 is peeled off from
second band 4.
To prevent aluminum sheet or band 2 from being completely
separated from the thermoplastic band 4 of lid 10, another strong
and non-peelable bonding is advantageously provided between
aluminum sheet 2 and band 4, within a zone 77 of composite band
and a fixed distance from the passage opening 15, hence from the
slit 5, or else in the immediate vicinity of the latter, although
always in a marginal zone of the lid. Said other bonding can also
be produced with a layer of adhesive of high adhering power 78
spread for example in the form of a thin strip over band 4 astride
two series or rows of juxtaposed lids or containers (see Figures 2
to 5).
Figure 5 illustrates various embodiments or
configurations of the slits 5, hence of the passage openinys 15, as
well as of the permanent bonding area of the aluminium sheet on the
thermoplastic band. For the sake of comprehension, it is assumed
in this Figure 5 that the aluminum sheet 2 and the sheet of
adhesive of low adhering power 3 have been removed and that zones
9588
or areas 72 and 78 reserved for the layers of adhesive with high
adhering power between aluminum sheet 2 and band 4 only
schematically indicated. Moreover, the composite lid band 1 is
represented therein in the form of cut lids permanently fixed on
05 the edge or rim of the corresponding containers 9.
ûn the lid lOa, it is noted that the slit 5 made in the
band 4 forms a closed loop, and is placed, with respect to the
container opening 11, so that its outline partly joins up with the
outline of said container opening 11, and thereafter extends
diagonally towards the center of said container opening. Part 6 of
the band 4, situated within the zone or area defined, or surrounded
by the slit 5, is provided at its upper part with a layer of
adhesive with strong adhering power, as is the case with zone 77,
78. The slit 5 is, understandably, sealed off by the
thermoplastic film 74 bonded tightly to the edge 12 of the
containers and adhering strongly to the lo~er face of band 4.
It is easy to understand that the action of peeling off
aluminum sheet 2 starting from the gripping corner or tip 75,
-- uncovers access opening 15 by tearing off sealing film 74 along the
aforementioned edge which coincides with the outline of access
opening 15. The operation of peeling off aluminum sheet 2 is
stopped as soon as the edge or border line 79 of the strong bonding
zone 77, 78 is reached.
Lid lOb comprises a slit 5 of which the outline coincides
with the outline of the container opening 11. In this case,
sealing film 74 will be torn off, during the peeling off operation,
in the immediate vicinity of the vertical wall of the container,
thereby giving a maximum opening. The peeling off operation is
stopped as soon as the edge or border line 79 of the strong bonding
zone 77, 78 bstween bands 2 and 4 is reached, said edge 79
coinciding in this case with one side of the slit 5.
In order to keep the partly peeled off aluminum band or
sheet 2 attached to the container - i.e. once the access or passage
opening 15 is uncovered, without having to use an extra layer of
adhesive with high adhering power, as in the case of lids lûa and
lZ795~8
lOb, sealing film 74 and thermoplastic band 4 will be
advantageously used (see Figures 5 to 7). To this effect, a slit 5
is made with non-jointed ends 80, 81, namely with spaced apart ends
leaving between them a folding zone 82 which makes it possible to
05 uncover the access opening 15 while being kept fixed to the
container 9 and holding together the assembly composed of the torn
part of film 74, of part 6 of band 4 and of aluminum sheet 2.
The slit 5 made in lid lOc is not closed up so as to form
a closed loop in the zone 82 situated opposite the gripping tip 75
and which will subsequently correspond to the folding zone of said
lid. This design is particularly advantageous wherein slit 5 is
situated near the side wall of the container 9 and thus
corresponds nearly to the edge of opening 11 of container 9.
Lid lOd has a slit 5 of which the outline coincides with
part of the outline of opening 11, the ends 80, 81 of which define
a folding zone 82 which is substantially rectilinear and parallel
to one of the sides of the container edge 12. The positlon or
location of this folding zone 82 is so selected that at least half,
and preferably more than half of the opening of the container 11
can be uncovered when the aluminum sheet is peeled off.
Obviously, the band or sheet can also be constituted of a
sheet of paper or of a band of polyester. Band 4 may be of PVC or
polyester. The sealing film 74 may be of polyethylene and band 8
may be of polypropylene or may even be a composite band.
