Note: Descriptions are shown in the official language in which they were submitted.
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CIGARETTE PACKAGE PROVIDED WTL INTERNAL ENVEID131- MADE FROM
POLYMER FILM Description
[001] Cigarette packaging with inner wrappings made of polymer film
[002] The invention concerns a cigarette packaging comprising at least one
outer
packaging, and an inner wrapping for cigarettes. The invention furthermore
concerns an inner liner.
[003] Cigarette packagings are conventionally constructed in such a way that
the
packaging contents, namely a collection of cigarettes, are surrounded by an
inner
wrapping. In the prior art, this inner wrapping consists of a cut sheet of
aluminium foil. an aluminium-paper lamination or a piece of metallised paper.
This inner wrapping is often imprinted or embossed. Earlier cut sheets are
today
conventionally replaced by inner wrappings made of paper. The inner wrapping
is
often imprinted or metallised, if necessary in combination with embossment, on
the outside.
[004] When manufacturing the packaging, the cigarettes are wrapped in this
inner
wrapping, the so-called inner liner, and the wrapped collection of cigarettes
are
folded by the packaging machine with the outer packaging, for example a flip-
top
lid packaging or a paper label.
[005] The inner liner can consist of printed paper, metallised paper or other
lamellar
materials. These materials are pulled onto the packaging machine off a roll
and
cut to the appropriate length. If necessary, selected perforations are made in
order
to produce a target cut-off point which makes possible a selected tearing open
of
the inner liner upon first opening of the packaging.
[006] Paper and metal films are particularly advantageous because of the
folding
properties and the tearing properties. In this type of use, the strips of
material
must feature good folding properties (dead-fold) which ensure that the
cigarettes
being wrapped are wrapped up firm enough to remain as a bundle up until the
point at which the outer packaging, is put in place. Furthermore, the tearing
behaviour performs an important role, in that a controlled opening of the
liner is
ensured. Finally, the cuts must feature a good flatness, in order that the
handling
is not hindered by the strips of material furling up.
[007] This set of properties is well fulfilled by paper and metallised papers.
Film
made of thermoplastic polymers have inherently poor folding properties and
therefore are generally not suitable material for this usage. Moreover,
plastic
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films in the form of small cuts tend to curl up, i.e. these cuts roll up along
or
across the length of the film strip all by themselves.
[008] As plastic films nevertheless often have advantages over paper both from
the
point of view of environmental aspects and in terms of cost, the substitution
of
paper in various uses is a request constantly put to the film manufacturer.
[009] So underlying the invention was the task of making available a film
suitable
for use as the inner liner of cigarette packaging, and which met the demands
of
this usage.
[010] This task is solved by the use of a single-layered or multilayered,
biaxially-
oriented film as the inner liner of a cigarette packaging, such that the film
contains
70 to 100% by weight of a polymer made of at least one aliphatic hydroxyl
carboxylic acid.
[011] The invention comes into use particular for flip packs and soft
packaging. The
inner liner made of polyhydroxycarboxylic acid film, preferably PSA film, is
particularly suitable for flip packs. These cartons conventionally consist of
thin
card. A piece of the carton serves to pick up the contents of the packaging,
namely a collection of cigarettes which is surrounded on all sides by the
folded
inner wrapping made of polyhydroxycarboxylic acid or PSA. There is a lid
disposed on a back side of the carton, which is connected to the carton over a
fold
line. Further details of the embodiment of flip packs are known and described
e.g.
in DE 43 33 462, a description to which explicit reference is made here.
[012] The collection of cigarettes, the contents of the packaging, is
surrounded on all
sides by the inner wrapping according to the invention. The unit so arising as
the
packaging contents is a block of cigarettes. According to the invention, a
film
made of polyhydroxycarboxylic acid, preferably a PLA film, is introduced to
the
cigarette wrapping in order to manufacture such a block of cigarettes.
[013] The film is cut to the suitable width for this purpose and pulled onto
the
packaging machine off a roll as a ream and cut to the appropriate length. The
shape of the cut depends on the type of folding coming into use. For example,
the
tailored film cut is laid around the collection of cigarettes according to the
principle of side folding. Connected to a continuous, closed bottom side are a
front side and a back side. An upper end wall is likewise formed by folding,
such
that interior pointed corners and trapezoid pointed edges are formed.
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[014] In a further embodiment, the inner wrapping of the upper area can be
provided
with a draw-off strap, a so-called flap. For this purpose a perforated line or
some
other kind of weakening line is made over the full width of the cut. Upon
first
opening of the package, the draw-off strap is detached by catching the outer
pointed edge.
[015] The cut is generally separated from the strips of material in such a way
that the
cut lies in the longitudinal direction. The strips of material can be provided
with
printing surfaces if necessary, which advantageously are arranged with a gap
between them in the direction running along the length of material. The cross
cuts
for dividing the cuts are carried across the film lengthwise. The exact
positioning
of the dividing line can be carried out with a print mark control because of
the
printer's imprints.
[016] Alternatively, the cut can be constructed in such a way that the width
of the
strip of film corresponds to the length of the cut. With this arrangement, the
cuts
are aligned normal to the length of the strip of material. In these cases, the
strip of
material is provided with continuing strips of print on both sides, in
particular of
varying widths.
[017] Cuts and techniques for folding the inner liner, units for imprinting
cuts and
further details and known in the prior art and described e.g. in DE 201 20 977
or
DE 43 33 462 or DE 25 11 241, to which explicit reference is made here.
[018] The packaging with inner liner constructed in the way described are
generally
additionally provided with an outer wrapping made of film, in particular
polypropylene film or cellophane.
[019] According to the invention, the inner liner is made of a biaxially-
oriented film,
which can feature one or several layers. The main constituent of the film is a
polymer made of at least one aliphatic hydroxyl carboxylic acid. In general,
the
film contains at least 70-100% polymers made of aliphatic
polyhydroxycarboxylic
acid, preferably PSA. Embodiments made of 80-99% by weight, preferably 85-
95% by weight of the named polymers, in each case relative to the weight of
the
film, are preferred.
[020] Surprisingly, a film made of polyhydroxycarboxylic acid, preferably PLA
is
excellent for use as inner liner. It was found that the film fixes in place
the
cigarette bundle sufficiently after the impaction. The film shows now
disruptions
during handling on the packaging machine. I turned out that the cuts have
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surprisingly little furling, sometimes none at all, and so avoid the problems
of
other thermoplastic films. Moreover, films are particularly advantageous,
because
with them a good stable workability is given even in fluctuating climatic
conditions. It was shown, the in comparison the paper, fluctuating
temperatures
or a fluctuating humidity hardly affects the film and its properties and has
no
effects on its use as inner liner and can always be handled equally well.
[021]
[022] Both single-layered and multilayered films made of aliphatic
polyhydroxycarboxylic acid are suitable for use according to the invention.
Multilayered films are generally constructed out of a thick base layer which
features the largest layer thickness and makes up 60 to <100% of the total
thickness of the film. This base layer is provided with (a) top layer(s),
preferably
on both sides but only on one side if necessary. In further embodiments,
additional intermediate layers or coatings of the outer surface of the
multilayered
film are possible, through which four or five-layered, coated or uncoated,
films
are obtained. The thickness of the top layer generally lies in a range from
0.5 to
pm, preferably 0.5 - 6 m, in particular 1 to 3 . The total thickness of the
film
according to the invention lies in range from 20 to 100 m, preferably 25 to 80
m,
in particular 30 to 60 m. The top layers are the layers with form the outer
layers
of the film. Intermediate layers are by naturally attached between the base
layer
and the top layers. Following embodiments to the layers of the film count
analogously in the same way for single-layered embodiments of the film.
[023] Surprisingly, films with a minimum thickness of 20 m are particularly
advantageous for use as inner liner according to the invention. If the
thickness of
the film lies under 20 m, then congestions occur on the machine. It was found
that surprisingly thin films function even better in the use according to the
invention. When the film thickness is too large, the film shows too large
reset
forces, so that the wrapped cigarettes slip out of the bundle before the outer
flip
pack can be applied. Therefore a maximum thickness of 100 m should not be
exceeded.
[024] The film, as well as the individual layers of the film if necessary,
contain(s) 70
to around 100% by weight, preferably 80 to 98% by weight of a polymer made of
at least one of the aliphatic hydroxycarboxylic acids, hereinafter also called
PHC
or polyhydroxy carboxulic acids. This means homopolymers or mix
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polymerisates, which are made up of polymeristae units of aliphatic hydroxyl
carboxylic acids. Among the PHC suitable for the present invention, poly
lactic
acids are particularly suitable. These are hereinafter called PLA (poly lactic
acid).
Here too, both homopolymers which are made up only of lactic acid units, and
also mix polymerisates which predominantly contain lactic acid units (>50%)
bonded with other aliphatic hydroxyl lactic acid units, are meant by the term
PSA.
[025] As monomers of the aliphatic polyhydroxycarboxylic acids (PHC),
aliphatic
mono-, di- or trihydroxycarboxylic acids, or their dimer cyclic esters, are
suitable,
among which lactic acid in its D- or L- form is preferred. These kinds of
polymers are known in the prior art and are commercially available. The
manufacture of poly lactic acids is likewise described in the prior art and
takes
place over catalytic ring-opening polymerisation of lactide (1,4-dioxane-3,6-
dimethyl 2,5-dione), the dimerised cyclic ester of the lactic acid, hence PSA
is
often also called polylactide. The manufacture of PSA is described in the
following publications: US 5,208,297, US 5,247,058 or US 5,357,035.
[026] Polylactic acids made up exclusively of lactic acid units are preferred.
In this
connexion PSA homopolymers containing 80-100% by weight L-lactic acid units,
corresponding to 0 to 20% by weight D-lactic acid units, are particularly
preferred. Even higher concentrations of D-lactic acid units can be contained
as
comonomers in order to decrease the crystallinity. If necessary, the
polylactic
acid can additionally feature various aliphatic polyhydroxycarboxylic acid
units as
comonomers from the lactic acid, for example glycolic acid units, 3-hydroxy
propanoic acid units, 2,2-dimethy1-3-hydroxypropanoic acid units or higher
homologues of the hydroxycarboxylic acids with up to 5 carbon atoms.
[027] Preferred are lactic acid polymers (PLA) with a melting point of 110 to
170 C,
preferably from 125 to 165 C, and a melt flow index (DIN measurement 53 735 at
2.16 N load and 190 C) of 1 to 50g/10 min, preferably from I to 30 g/10 min.
The molecular weight of the PLA lies in a range of at least 10 000 to 500 000
(counting mean), preferably 50 000 to 300 000 (counting mean). The glass
transition temperature lies in the Tg lies in a range from 40 to 100 C,
preferably
40 to 80 C.
[028] The individual layers of the film each contain 70 to around 100% by
weight of
the previously described polymers, preferably 80 to 98% by weight, as well as
additional additives if necessary, like neutralising agents, stabilisers,
lubricants,
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static inhibitors and fillers. They are advantageously added to the polymer or
the
polymer mixture before melting on. Phosphorous bonds, like phosphoric acids or
phosphoric acid esters, for example, are introduced as stabilisers. The
individual
layers can basically feature the same composition as regards polymers and
additives. In general, the composition of the base layer is different from the
composition of the remaining layers. In particular, additives like anti-
blocking
agents or lubricants are added to the top layers, whereas fillers or pigments
are
preferably introduced into the base layer. Construction and composition of the
individual layers of the film can nevertheless vary within wide boundaries.
[029] It was found that transparent and white embodiments without vacuoles are
especially well suited for this use. It is known about polypropylene films
that
opaque PP films with vacuoles in the base layer feature better folding
properties
than transparent PP films. The vacuole-free PLA films surprisingly also show
very good folding properties in this use in comparison to vacuolated
embodiments. In the sense of the present invention, transparent films are to
be
understood as those with a light permeability according to ASTM-D 1003-77 lies
over 75%, preferably over 95%. White PLA films are coloured white by the
addition of white pigment, but have no vacuoles either. These embodiments
generally contain TiO2 in a quantity of 1 ¨ 12% by weight in at least one
layer, if
necessary several. Basically, TiO2 can be added in these quantities to one or
both
top layers or also to one or both intermediate layers.
[030] The addition of opaque or white-opaque embodiments of the film is
basically
also possible. These films contain vacuole-initiating fillers in the base
layer, for
example cycloolefin copolymer (opaque films) and, if necessary, additional
pigments (white-opaque films). In this case, too, TiO2 is also preferred as
pigment
and is introduced in a quantity of up to 10% by weight, preferably 1 to 8% by
weight, in each case relative to the base layer.
[031] If necessary, the film can be coated in order to optimise further
properties of
the film. Typical coatings are adhesion-enhancing, slip-improving or dehesive-
operating coatings. If necessary, these additional coatings can be applied
over in-
line coating by means of aqueous or non-aqueous dispersions before lateral
stretching or off-line.
[032] In a further embodiment, the films are metallised as inner liner before
use.
Upon use as inner-liner, the metallised side fauns the visible side. In a
further
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embodiment, the film can be metallised on both sides. This embodiment has the
additional advantage that direct contact between the cigarettes and the film
is
avoided, so that no detriments to the taste of the cigarettes because of the
film are
possible, or rather they are extensively prevented.
[033] In a further embodiment, the metallised or non-metallised film can be
additionally provided with an embossment which on the one hand has a
decorative
character, and which contributes towards a further improved flatness.
Surprisingly, after metallisation and imprinting the films can be handled just
as
well as the paper inner-liner used until now. What is more, the embossed
metallised films come very close to the topical appearance of metallised
papers.
[034] The PHC film is manufactured according to the coextrusion procedure
known
in itself. Within the scope of this procedure, the melt(s) corresponding to
the
layers of the film are coextruded through a flat die, the multilayered film so
obtained is pulled off for hardening on one or several roller(s), the film is
subsequently biaxially stretched (oriented), the biaxially-stretched film is
heat set
and, if necessary, corona- or flame-treated on the surface layer intended for
treatment.
[035] The biaxial stretching is generally carried out sequentially. In so
doing,
stretching preferably happens first in the longitudinal direction (i.e. in the
machine
direction, = MD direction) and subsequently in the lateral direction (i.e. at
a right
angle to the machine direction, = TD direction). This leads to an orientation
of the
molecular chains. The stretching in the longitudinal direction preferably
takes
place with the help of two rollers running at different speeds, corresponding
to the
desired stretch ratio. For the lateral stretching, a corresponding clip frame
is
commonly used. Further description of the film manufacture is carried out
according to the example of a flat film extrusion with subsequent sequential
stretching.
[036] The melt(s) are pressed through a flat die (sheet die), and the film
pressed out
is pulled off on one or several outfeed rollers at a temperature of 10 to 100
C,
preferably 20 to 80 C, such that it cools off and hardens.
[037] The film so obtained is then stretched along and across the direction of
extrusion. The longitudinal stretching will preferably be carried out at a
roller
temperature of the stretch roller of 40 to 130 C, preferably 50 to 100 C,
advantageously with the help of two rollers running at different speeds,
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corresponding to the desired stretch ratio; the lateral stretching preferably
at a temperature of
50 to 130 C, preferably 60 to 120 C with the help of a corresponding clip
frame. The
longitudinal stretch ratios can vary within a range of 1.5 to 8. In the
manufacture of films
with a base layer containing vacuole-initiating fillers a high longitudinal
stretch ratio of 3 to 6
is preferred, whereas films with a transparent base layer are preferably
stretched within a
range of 1.5 to 3.5. The lateral stretch ratios lay in the range from 3 to 10,
preferably 4 to 7.
[038] Attached to the stretching of the film is its heat setting (heat
treatment), where the film
is held converging around 0.1 to 10 s long at a temperature of 60 to 150 C
(convergence up to
25%). Subsequently the film is wound up in the conventional manner with a
batcher.
[038a] A further embodiment of the invention may relate to use of a single-
layered or
multilayered, biaxially-oriented film as inner liner of cigarette packaging,
wherein the film
contains 70 to 100% by weight of polymer of at least one aliphatic
polyhydroxycarboxylic
acid and the film has a total thickness of at least 20 to 100 i_tm.
[039] The following measured values were used to characterise the raw
materials and the
films:
[040] The invention will hereinafter be explained on the basis of the
following execution
examples:
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[041] Example 1:
[042] A transparent, three-layered PLA film with a thickness of around 30!_tm
was
manufactured by extrusion and subsequent incremental orientation in the
longitudinal and lateral directions. The base layer consisted of almost 100%
by
weight polylactic acid with a melting point of around 160 C. The layer
additionally contained stabilisers and neutralising agents in conventional
quantities. Both sealable top layers were fundamentally made up of an
amorphous
polylactic acid, such that this polylactic acid features an L/D ratio of
around
40/60. In addition, the top layers each contained 0.1% y weight Si02-based
particles as anti-blocking agents. The thickness of the top layers each came
to
2.5pn.
[043] The manufacturing conditions in the individual procedural steps were:
[044] Extrusion: temperatures 170 ¨ 200 C
[045] Temperature of the outfeed roller: 60 C
[046] Longitudinal stretching: temperature: 68 C
[047] Longitudinal stretch ratio: 2.0
[048] Lateral stretching: temperature 88 C
[049] Lateral stretch ratio (effective): 5.5
[050] Fixation: temperature 75 C
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[051] Convergence: 5%
[052] Example 2:
[053] A film was manufactured as is described in example 1. In contrast to
example
1, no top layer was attached. For the rest, the composition and the
manufacturing
conditions were unchanged. A transparent film, but a single-layered film with
a
thickness of 251.1m, was again manufactured.
[054] Example 3:
[055] By extrusion and subsequent incremental orientation in the longitudinal
and
lateral directions, an opaque, single-layered PLA film with a thickness of
30pm
was manufactured. This layer was around 95% by weight made up of a polylactic
acid with a melting point of 135 C and a melt flow index of around 3 g/10min
and
a glass transition temperature of 60 C and around 5% by weight COC (Ticona
Topas 6013) with a Tg of 140 C. The layer additionally contains stabilisers
and
neutralising agent in conventional quantities. The manufacturing conditions in
the
individual procedural steps were:
[056] Extrusion: temperature 170 ¨ 200 C
[057] Temperature of the outfeed roller: 60 C
[058] Longitudinal stretching: temperature: 68 C
[059] Longitudinal stretch ratio: 4.0
[060] Lateral stretching: temperature: 88 C
[061] Lateral stretch ratio (effective): 5.5
[062] Setting: temperature: 75 C
[063] Convergence: 5%
[064] In this way, an opaque film with characteristic pearlescent shine and a
reduced
density of around 0.75 g/cm3 is obtained.
[065] The films were introduced on a commercial cigarette packaging machine as
inner liner and could be used without huge problems. The non-vacuolated films
according to example 1 and 2 showed themselves to be especially advantageous.
[066] In contrast, biaxially oriented polypropylene films could not be adopted
in this
usage. Because of strong reset forces of the material, the individual
cigarettes
could not be packaged.
