Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02221426 1997-11-13
Cold Formable l.~m;n~te Films
The present invention relates to cold-formable l~min~te. films containing a barrier layer that is
impermeable to water vapour and gases and on both sides of the barrier layer at least one
5 plastic layer, and relates also to the use of the l~min~te films.
So called blister packs or push through packs are known. For example plastic films or plastic
l~min~tes or plastic l~min~tes containing a metal foil are deepened in such a manner that a
plurality of recesses or cups is produced. Shoulders are formed between the individual
10 recesses. The shoulders run completely round each recess and form a flat shoulder area. The
materials prepared this way form the base part of a blister pack. The base parts may be filled
with substances i.e. the contents. Known contents for blister packs are e.g. tablets, capsules,
dragées etc., from the pharmaceutical field, single or if desired more than one in each recess.
After that, the base part is closed off by sealing a lidding foil such as a metal foil, usefully
15 alumi~ foil or a l~min:~tf film containing e.g. a sealing layer and a metal foil on to the
shoulders of the base part by means of the sealing layer. To remove the contents, for example
a tablet or capsule, the recess is pressed from the base side and the tablet or capsule pressed
from within against the lid containing the metal foil above the recess. As a result of the
inelasticity of the lid material, the lid m~t~ri~l tears and affords access to the contents. In
20 another version the lid m~teri~l can be peeled away under the pressure of the contents or the
lid material can be grasped by a flap and peeled off.
In known blister packs which, as those described above, are manufactured out of a base part
featuring recesses and a smooth lid part, it is n~cess~ry to employ relatively thick materials in
25 order to have sufficient wall thickness after deepening and, in relation to the size of the
recesses, relatively broad shoulders are a pre-requisite for a blister pack that is sealed against
moisture and air. As the known films exhibit only limited formability, the ratio of recess
diameter to depth can not be chosen at will i.e. the walls of the recess are only moderately
steep.
The object of the present invention is to propose a push-through or blister pack e.g. for
capsules, tablets or powders containing active ph~rm:l~eutical ingredients or diagnostics,
having a superior protective action against the uptake of moisture and gases. It should be
possible thereby to keep the size of the pack small in relation to the number of recesses, for
35 example by steep walls in the recesses or as a whole by deeper forming. It should also be
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possible e.g. to provide smaller shoulder areas and, at the same time still ensure safe water
vapour and moisture proof sealing between the base part and the lid part.
That objective is achieved by way of the invention in that the l~min~te film exhibits the a
S layered structure of the following kind and order:
a) a first plastic f~m comprised of a stretched PVC film or an oriented polyester film
and
b) a metal foil and
c) a second plastic film in the form of a stretched PVC film, an oriented polyester film
or an oriented polyamide film.
.
Preferred are cold-formable l~min~t~ films exhibiting the following sequence of layers:
a) a first plastic film comprised of a stretched PVC film
b) a metal foil and
c) a second plastic film in the form of an oriented polyester film or an oriented
polyamide film.
20 Further preferred cold-formable l~min~te films according to the present invention are those
containing the following sequence of layers:
a) a first plastic film comprised of an oriented polyester film and
b) a metal foil and
c) a second plastic film in the form of an oriented polyester film or an oriented
polyamide film.
The first and second plastic films may - independent of each other - be a monofilm or a
l:lmin~tl~ film of two or more layers of the same or different plastics. In order to influence the
30 forming behaviour and to keep the amount of material within economic limits, the first and
second plastic films, which are processed to providing the present l~min~te films, are
employed in practical and preferable thicknesses. For example, the stretched PVC films are
10 to 200 ~lm thick, usefully 10 to 100 ,um, preferably 30 to 60 llm thick, the oriented
polyester films S to 60 llm, usefully 10 to 30 llm and preferably 12 to 25 ,um thick, the metal
35 foils 5 to 200 llm, usefully 20 to lO0 llm and preferably 45 to 60 ,um thick, and the oriented
polyamide films S to 40 ,um, usefully 10 to 30 ~lm and preferably 15 to 25 ,um.
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The metal foil may be of steel, iron or copper and is preferably an ~ minillm foil. The
all-mini~-m foil may usefully be an al~lminium alloy AlFeMn alloy such as AlFel.SMn, AlFeSi
or AlFeSiMn, for example with a purity of 97.5 % and higher, preferably 9~.5 % and higher.
The metal foil is preferably a continuous and uninterrupted foil, which is also texture-free and
5 isotropic.
The metal foil, or the ~hlminillm foil, is either not pre-treated with a primer or is pre-treated
with a primer e.g. on one or both sides.
10 Suitable primers may e.g. be of the epoxy resin type or a polyurethane.
The cold-formable l~min~t~ films contain e.g. stretched PVC films, oriented polyester films
and oriented polyamide films. Suitable thermoplastics for producing these films are described
below.
The PVC films are films based on halogen-containing polymers, i.e. polymers of the
vinylchloride (PVC) type or vinyl plastics containing vinylchloride constituents in their
structure such as copolymers of vinylchloride and vinyl-esters of aliphatic acids, copolymers
of vinylchloride and esters of acrylic or methacrylic acids or acrylnitrile, copolymers of
20 vinylchloride and dein compounds and unsaturated dicarboxyl acids or their anhydrides,
copolymers of vinylchloride and vinylchloride with unsaturated aldehydes, ketones etc., or
polymers and copolymers of vinylidenchlorides and vinylchloride or other polymerisable
compounds. The vinyl based thermoplastics may also be made soft in a known manner using
primary or secondary softeners.
Films of PVC are at least monoaxially (oPVC) stretched or in some cases may be biaxially
stretched. If the stretched PVC films are monoaxially stretched, their reduction in thickness is
preferably in the range of 30 to 40%.
30 If the plastic films are of polyesters (PET films), then examples for the polyesters are
polyalkylene-terephth~l~tes or polyalkylene-isophthalates with alkylene groups or radicals
with 2 to 10 carbon atoms or alkylene groups with 2 to 10 carbon atoms which areinterrupted at least by one -O-, such as e.g. polyethylene-therphthalate, polypropylene-
therephthalate, polybutyleneterephthalate (poly-tetra-methylene-terephth~l~te), poly-deca-
35 methylene-terephthalate, poly-1.4.cyclo-hexyl-dimethylol-terephthalate or polyethylene-2.6-
naphthalene-dicarboxylate or mixed polymers of polyalkylene-terephthalate and polyalkylene-
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isophthalate whereby the fraction of isophth~l~te amounts e.g. to 1 to 10 mol %, mixed
polymers and terpolymers, block polymers and grafted modifications of the above mentioned
substances. Other useful polymers are known in the field by the abbreviation PEN.
5 Other polymers are copolymers of terephthalic acid and a further polycarboxyl acid with at
least one glycol. Useful in that connection are the copolymers of terephthalic acid, ethylene
glycol and a further glycol. Preferred are glycol-modified polyesters, known in the field as
PETG.
10 Further useful polymers are polyalkylene-terephth~l~tes with alkylene groups or radicals with
2 to 10 carbon atoms and polyalkylene-terephthalates with alkylene groups or radicals with 2
to 10 carbon atoms, which are interrupted by one or two -O-. Further preferred polyesters
are polyalkylene-terephthalates with alkylene groups or radicals with 2 to 4 carbon atoms.
Belonging to these polyethylene-terephth~l~tes are also A-PET, PETP and the already
15 mentioned PETG or G-PET. Very highly preferred are polyethylene-terephth~lat~ films. The
films of polyester are monoaxially or preferably biaxially oriented.
If the plastic films are polyamide films (PA), then the following belong to these polyamides
e.g.: polyamide 6, a homopolymer of ~-caprolactum (polycaprolac- tam); polyamide 11,
20 polyamide 12, a homopolymer of c~l~llrinl~tam (polylaurin- lactam); polyamide 6.6, a
homopoly-condensate of hexamethylene-diamine and adipinic acid (polyhexamethylene-
adipamide); polyamide 6.10, a homopoly-condensate of hexamethylene-diamine and sebacinic
acid (polyhexamethylene-seb~c~mide); polyamide 6.12, a homopoly-condensate of hexa-
methylene-diamine and dodecandic acid (polyhexamethylene- doclec~n~mide) or polyamide
25 6-3-T, a homopoly-condesate of trimethylhex~methylene-di~mine and terephthalic acid
(polytrimethyl-hexamethylene-terephth~l~mide), and mixtures thereof. The films of
polyamide are monoaxially or preferably biaxially oriented (oPA).
In order to control the sealing properties, the present l~min~te films may exhibit on one or
30 both free sides, sealing layers such as sealing films or organic sealing coatings e.g. based on
polyolefins such as polyethylenes, polyacrylates, PVC resins, polyvinylidenchlorides, EVA
polyethylene-terephthalates, in particular the A-PET type, etc. The free sides or at least one
of the free sides, especially of the oriented polyester films, may be coated with EVA
(ethylene/vinylalcohol copolymer) or with an amorphous polyester sealing layer of the PET-
35 A type.
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The individual layers and in particular films i.e. the first plastic film against the metal foil
and/or the second plastic film against the metal foil and any sealing films coming into contact
with the free sides of the l~rnin~te film may be joined together by means of a bonding agent
and/or l~min~te adhesive.
Suitable l~min~te adhesives may be solvent-cont~ining, solvent-free or aqueous acrylic
adhesives or polyurethane adhesive systems. However, also adhesives that are cured under
the ir~luence of radiated energy (e.g. UV; electron beams) may be employed.
10 Preferred are polyurethane based l~min;~te adhesives.
As bonding agent one may employ e.g. products based on di-isocyanate or aliphatic poly-
esters.
15 The l~min~ting adhesive, like the bonding agent may be used in amounts of 0.5 to 10 g/m2
preferably 2 - 8 g/m2 and especially from 3 to 6 g/m2 . The l~min~ting adhesive may also be
employed in such quantities that it forms layers that are at least 0.1 ,um thick and at most
12 ,um thick.
20 The surface of the metal foil may exhibit improved adhesion for adhesive or organic coatings
or for an extrusion layer as a result of an applopriate pre-treatment (e.g. brushing, chromate
treatment, ionising, ozone, corona, flame or plasma treatment). In order to promote and
improve the bonding between the plastic films or extruded layers by means of organic coat-
ings, bonding agents or l~min~ting adhesives, it is often useful to endow the films on the sides
25 facing the adhesive or the extrudates with adequate surface tension. The increase in surface
tension may be effected preferentially by the ionising, ozone, flame or plasma treatment.
The l~min~te films according to the invention may exhibit a sealing layer, such as a sealing
film or an organic sealing coating of the above mentioned substances, on one or both free
30 sides, - or on a side of the packaging container made from it and facing the contents, also
known as the inner side, in some cases also on the side of the container facing out i.e. the
outer side. The packaging container may be a base part of a push-through pack featuring a
shoulder region and recesses therein. The sealing layer makes it possible to attach a lid to this
container i.e. to the base part made of cold formed l~min~te film according to the present
35 invention. Such lids may be for example lidding foils which are sealed on at the shoulders of
the packaging container. Suitable lidding foils may contain a metal foil such as an ~hlminillm
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foil and plastic films and/or organic coatings may be present on one or both sides of the metal
foil. An outermost layer in the form of a sealing layer may be provided at least on one side of
the lidding foil. The base part and the lidding foil may be joined together via the sealing layer
on the lidding foil or via the sealing layer on the base part, or via both sealing layers.
s
The l~min~te films may exhibit organic coatings and/or printed patterns on the inner and/or
outer sides or facing the inner and/or outer sides - in each case referring to a packaging
container made from the l~min~te film according to the invention. For example, the first
and/or the second film of the l~min~te may exhibit a reverse image on the side facing the
10 metal foil. A reverse image is especially suitable for transparent and translucent films. It is
also possible to provide printed patterns on the outer side of the first and/or second film and,
as the case requires, to cover this over with an organic coating. The outer and/or inner sides
of the l~min:~te may also be provided with an organic coating; a printed pattern may also be
provided on the said organic coating and/or may be applied on the packaging line.
The present invention relates also to blister packs or push-through packs or base parts for
these, made from a cold formed l:~min~te film according to the present invention.
The desired blister or push-through pack and in particular the base parts for these may be
20 made from the l~min~tP film according to the invention e.g. by means of a deepening process
such as stretch drawing i.e. mechanical cold forming using a shaping tool. During stretch
drawing the l~min~tP film is held securely between the die and the press pad while the
shaping tool forces the l~rnin~te film to adopt the desired shape by stretching it. The forming
process may be performed e.g. cold or at slightly elevated temperatures of up to 50 ~C. The
25 l:lmin~tP films according to the invention, because of their behaviour during forming, may be
used preferentially for blister and push-through packs with recesses having steeper sidewall
regions. For example it is possible to achieve an inclination of 50 degrees of angle and higher
up to almost 90 degrees of angle with respect to the horizontal surface of the l~min~te film.
The ratio of diameter to depth of an individual recess may e.g. amount to 2.5 to 3Ø The
30 push-through packs made from the l~min:lte film according to the invention may have edge
lengths e.g. of 30 to 200 mm, and the shoulder regions at the edges and between the recesses
may e.g. have a width of 1 to 10 mm, preferably 3 to 6 mm. Such blister packs or push-
through packs may exhibit e.g. 2 to 200, usefully 6 to 60 and advantageously 10 to 30
recesses, cups or compartments to accommodate e.g. a tablet, capsule, ampoule, dragée or
35 powders. One recess is also capable of accommodating more than one single item - or instead
of the above mentioned contents - e.g. small technical items. During stretch forming the
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l~min:~e film is subjected purely to elongation. As a result the plastic on the packaging facing
outwards, as a rule the second plastic film in the l~min~te, exhibits a high degree of work
hardening during the stretching operation and a high capacity for elongation. During the
elongation of the second plastic film the ~hlminillm foil is supported mechanically. Con-
5 sequently, elongations can be achieved that are far beyond the limit of elongation exhibitedby ~luminium foil by itself.
The preferred biaxially stretched plastic films in the l~min~tP films according to the invention
enable isotropic flow of the l~min~te film to be achieved, and with that avoid the concent-
10 ration of stress. As soon as the metal foil begins to neck during the forming operation, theplastic film is able to take on the load at that site as a result of the high degree of work hard-
ening experienced during shaping. During stretch drawing the material of the l~min~te film
flows preferably from the width than from the thickness, R values of > 1 being advantageous.
Further, the l~min~te film exhibits a high degree of elongation at fracture. A further preferred
15 property of the l~min~e film according to the invention that can often be observed is a small
degree of spring-back after forming.
The first plastic film, which in packaging made from the l~min~te film according to the
invention faces the inside and the product, is harmless from the physiological standpoint and
20 may exhibit only a small or preferably no capacity for the uptake of gases and fluids. The first
plastic film preferably exhibits high rigidity. A further preferred property of the plastic film is
the mechanical support it affords the ~hlminillm foil during elongation. The blister packs or
push-through packs made from the l~min~te film according to the invention enable a
reduction of blister area of up to 10 ~o to be achieved as a result of the properties of the
25 l~min~te films and the greater degree of forming that can be achieved as a consequence
thereof.
Figure 1 shows schP.m~ti~lly the structure of the l;lminA~e film 1 according to the invention.
The l~min~tP film 1 exhibits a metal foil 11 which is clad on one side by the first plastic film
- 30 10 and on the other side by the second plastic film 12. The arrows 13, 14 indicate that a
primer, a bonding agent and/or a l~min~ting adhesive may be provided between the individual
layers. If the layers 10, 11 themselves can not be sealed or only inadequately sealed. a sealing
layer in the form of an organic sealing coating or sealable film may be provided on the free
side 15 of the first plastic film 10 and/or on the free side 16 of the second plastic hlm 12. As
35 a rule the second plastic film 12 forms the outside of a pack while the first plastic film 10
faces the contents of the pack.
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