U.S. patent application number 14/441913 was filed with the patent office on 2015-11-05 for foodstuffs packaging containing a film with properties providing a barrier to mineral oils.
The applicant listed for this patent is TREOFAN GERMANY GMBH & CO. KG. Invention is credited to Yvonne DUPRE, Thomas GOTTFREUND, PETRA HADE.
Application Number | 20150314939 14/441913 |
Document ID | / |
Family ID | 47323810 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150314939 |
Kind Code |
A1 |
HADE; PETRA ; et
al. |
November 5, 2015 |
FOODSTUFFS PACKAGING CONTAINING A FILM WITH PROPERTIES PROVIDING A
BARRIER TO MINERAL OILS
Abstract
The present invention relates to foodstuffs packaging containing
a polyolefin-based film with properties providing a barrier to
mineral oils.
Inventors: |
HADE; PETRA; (Quierschied,
DE) ; DUPRE; Yvonne; (Enkenbach-Alsenborn, DE)
; GOTTFREUND; Thomas; (St. Ingbert, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TREOFAN GERMANY GMBH & CO. KG |
Neunkirchen |
|
DE |
|
|
Family ID: |
47323810 |
Appl. No.: |
14/441913 |
Filed: |
November 8, 2013 |
PCT Filed: |
November 8, 2013 |
PCT NO: |
PCT/EP2013/003369 |
371 Date: |
July 22, 2015 |
Current U.S.
Class: |
426/124 |
Current CPC
Class: |
H01Q 1/42 20130101; B32B
27/306 20130101; B32B 2439/70 20130101; B65D 77/02 20130101; H01Q
1/225 20130101; B32B 2255/10 20130101; B32B 2255/26 20130101; B32B
27/10 20130101; C08J 7/0427 20200101; G01F 23/284 20130101; B32B
2307/518 20130101; C08J 7/042 20130101; C08J 2433/06 20130101; B32B
7/12 20130101; C08J 2323/10 20130101; C08J 2423/08 20130101; B32B
27/32 20130101; B32B 2307/4026 20130101; H01Q 21/065 20130101; C08J
2427/08 20130101; H01Q 19/062 20130101; B32B 2272/00 20130101 |
International
Class: |
B65D 77/02 20060101
B65D077/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 2012 |
EP |
12007669.0 |
Claims
1.-24. (canceled)
25. A foodstuff packaging comprising: a) a foodstuff, b) a
polyolefin-based film which film encases the foodstuff, c) a
cardboard based on recycled cardboard, which encases the
polyolefin-based film, in particular the film based on biaxially
oriented polypropylene (boPP) films, containing the foodstuff,
wherein the polyolefin-based film comprises at least one coating
comprising (i) acrylate polymer and/or (ii) halogen-containing
vinyl polymers and/or vinylidene polymers and/or (iii) polymers
based on vinyl alcohol (VOH), and the coating is present at least
on the side of the film facing towards the cardboard based on
recycled cardboard.
26. The foodstuff packaging according to claim 25, wherein the film
and/or the cardboard does not have any metallization preventing the
migration of mineral oils into the packaged foodstuff).
27. The foodstuff packaging according to claim 25, wherein the film
is monolayered or multi-layered and comprises a base layer
containing at least 70% by weight of the polyolefin in relation to
the weight of the layer.
28. The foodstuff packaging according to claim 27, wherein the
polyolefin-based film is a film based on biaxially oriented
polypropylene (boPP) films and the base layer contains 85 to 95% by
weight, of the polyolefin, in each case in relation to the weight
of the layer.
29. The foodstuff packaging according to claim 28, wherein the film
is monolayered and contains 90 to 100% by weight, of propylene
polymers of which the melting point is 120.degree. C. and which
have a melt flow index from 1 to 10 g/10 min at 230.degree. C. and
a force of 21.6 N (DIN 53735).
30. The foodstuff packaging according to claim 25, wherein the
propylene polymer is a mixture of propylene homopolymers and/or
copolymers and/or terpolymers and other polyolefins wherein the
mixture contains at least 50% by weight of propylene polymer.
31. The foodstuff packaging according claim 25, wherein the
polyolefin film contains pigments in a quantity from 0.5 to 10% by
weight.
32. The foodstuff packaging according to claim 25, wherein the
polyolefin-based film has a thickness from 20 to 100 .mu.m.
33. The foodstuff packaging according to claim 25, wherein the
polyolefin-based film comprises, on one or both sides, an adhesion
promoter made of polyethylene imine, to which the coating/s is/are
applied.
34. The foodstuff packaging according to claim 34, wherein the
coating is present on both sides of the film.
35. The foodstuff packaging according to claim 25, wherein the
coating of the film on each side has in each case a total thickness
between 0.4-5 .mu.m.
36. The foodstuff packaging according to claim 35, wherein the
coating is multi-layered and, with a coating made of
halogen-containing vinyl polymers and/or vinylidene polymers,
initially has a secondary primer layer based on vinyl
acetate/acrylate, and the layer thickness of the secondary primer
layer comprises 50-100% of the layer thickness of the coating made
of halogen-containing vinyl polymers and/or vinylidene
polymers.
37. The foodstuff packaging according to claim 25, wherein acrylate
is an acrylate homopolymer and/or acrylate copolymer based on alkyl
acrylates.
38. The foodstuff packaging according to claim 25, wherein the
halogen-containing vinyl polymer and/or vinylidene polymer is based
on vinyl chloride and/or is vinyl chloride, which preferably
comprises a copolymer based on vinyl acetate or acrylate.
39. The foodstuff packaging according to claim 25, wherein the
coating material made of a polymer based on vinyl alcohol (VOH)
comprises a mixture of ethylene vinyl alcohol (EVOH) and polyvinyl
alcohol, and said mixture comprising 5-15% by weight of a mixture
of ethylene vinyl alcohol and polyvinyl alcohol, in the ratio
0.8-1.2 to 1.2-0.8 (ratios by weight).
40. The foodstuff packaging according to claim 25, wherein the
quantity of coating per side of the film (after drying) is between
0.5 and 1.0 g/m.sup.2 for coating materials made of polymers based
on vinyl alcohol (VOH), and the layer thickness is 1 to 1.5 .mu.m
(.+-.0.2 .mu.m).
41. The foodstuff packaging according to claim 25, wherein the
quantity of coating per side of the film after drying is between
0.5 and 1.5 g/m.sup.2 for coating materials based on acrylate, and
the layer thickness is 1 to 1.5 .mu.m.
42. The foodstuff packaging according to claim 25, wherein the
quantity of coating per side of the film after drying is between
2.5 and 4 g/m.sup.2 for coating materials based on
halogen-containing vinyl polymers and/or vinylidene polymers,
wherein the above quantity includes the secondary primer layer
based on vinyl acetate/acrylate, and the layer thickness is 1.5 to
2.0 .mu.m (.+-.0.2 .mu.m).
43. The foodstuff packaging according to claim 25, wherein the
recycled cardboard contains at least 300-1000 mg/kg mineral
oil.
44. The foodstuff packaging according to claim 25, wherein the film
comprises a barrier for the mineral oils present in the recycled
cardboard and at most 1%, of the MOSH 14-24 fraction present in the
recycled cardboard diffuses into a foodstuff' simulant when the
proportion of the fraction MOSH 14-24 in the mineral oil of the
recycled cardboard is at least 30% by weight.
45. The foodstuff packaging according to claim 25, wherein the film
comprises a barrier for the mineral oils present in the recycled
cardboard and at most 1.6% of the MOSH 24-35 fraction present in
the recycled cardboard diffuse into a foodstuff simulant when the
proportion of the fraction MOSH 24-35 in the mineral oil of the
recycled cardboard is at least 10% by weight.
46. The foodstuff packaging according to claim 25, wherein the film
comprises a barrier for the mineral oils present in the recycled
cardboard and at most 0.5% of the MOAH 14-24 fraction present in
the recycled cardboard diffuses into as foodstuff simulant when the
proportion of the fraction MOAH 14-24 in the mineral oil of the
recycled cardboard is at least 10% by weight.
47. The foodstuff packaging according to claim 25, wherein the film
comprises a barrier for the mineral oils present in the recycled
cardboard and at most 3.5%, of the MOAH 24-35 fraction present in
the recycled cardboard diffuse into a foodstuff simulant when the
proportion of the fraction MOAH 24-35 in the mineral oil of the
recycled cardboard is at least 1% by weight.
48. The foodstuff packaging according to claim 25, wherein the
foodstuffs packaging consists of the cardboard and the film and
does not comprise any further metal layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a national stage application (under
U.S.C. .sctn.371) of PCT/EP2013/003369, filed Nov. 8, 2013, which
claims benefit of European Application No. 12 007 669.0, filed Nov.
12, 2012, both of which are incorporated herein by reference in
their entirety.
[0002] The present invention relates to a foodstuffs packaging
containing a polyolefin-based film with properties providing a
barrier to mineral oils.
[0003] Polyolefin-based films, in particular biaxially oriented
propylene (boPP) films, are nowadays used as packaging films in a
wide range of applications. Polypropylene films are characterised
by many advantageous use properties, such as high transparency,
gloss, barrier to water vapour, good printability, rigidity,
penetration strength, etc. The polypropylene films can be used both
as transparent films and as opaque films.
[0004] The above films are often also used in combination with
other packaging materials, in particular in the field of
foodstuffs.
[0005] For foodstuffs packaging, cardboard packaging is often used
that, due to its availability, is often present in the form of
recycled cardboard. This results in problems, since recycled
cardboards typically contain 300-1000 mg/kg mineral oil with a
relatively low molar mass (primarily n-C18 to n-C22) and a content
of aromatic components between 15-20% (opinion no. 008/2010 of the
Federal Institute for Risk Assessment "BfR" of Sep. 12, 2009).
[0006] The mineral oil mixtures detected in recycled cardboard are
paraffin-like (open-chained, usually branched) and naphthene-like
(cyclical) hydrocarbons that are referred to as "mineral oil
saturated hydrocarbons" (MOSH), and also aromatic hydrocarbons, or
"mineral oil aromatic hydrocarbons" (MOAH), which consist primarily
of highly alkylated systems (see Biedermann M, Fiselier K, Grob K,
2009, "Aromatic hydrocarbons of mineral oil origin in foods: Method
for determining the total concentration and first results. Journal
of Agricultural and Food Chemistry 57: 8711-8721).
[0007] Insofar as no suitable precautionary measures are taken, for
example by metallisation of the cardboard, there is thus the risk
that the above-specified mineral oil mixtures will contaminate the
foodstuffs to be packaged or already packaged.
[0008] First approaches for using films based on polyolefin films,
in particular biaxially oriented polypropylene (boPP) films, as
barrier to the above-specified mineral oil mixtures show that the
polyolefin films alone do not effectively prevent the migration.
The films thus require an additional finishing in order to act as a
barrier to the above-specified mineral oil mixtures.
[0009] By way of example, films that have a metallisation with
sufficient optical density are suitable. This metal layer forms an
effective barrier against the mineral oils. For some applications,
however, such metal layers are undesirable for aesthetic reasons or
for cost reasons. In particular, these metal layers cannot be used
when the film packaging is to be transparent. Furthermore, the
efficacy as a barrier is also dependent on the quality of the
coating, such that only a high-quality costly metallisation serves
this purpose.
[0010] The object of the present invention was to provide a
polyolefin-based film, in particular a film based on biaxially
oriented polypropylene (boPP) films, for foodstuffs packaging
formed from recycled cardboard, which film has a sufficient barrier
to mineral oil mixtures and at the same time retains the good
application properties, such that a contamination of the foodstuff
to be packaged or already packaged by the mineral oil mixture in
the recycled cardboard is avoided.
[0011] The present invention thus relates to a foodstuffs packaging
comprising: [0012] a) a foodstuff, [0013] b) a polyolefin-based
film, in particular a film based on biaxially oriented
polypropylene (boPP) films, which film encases the foodstuff,
[0014] c) a cardboard based on recycled cardboard, which encases
the polyolefin-based film, in particular the film based on
biaxially oriented polypropylene (boPP) films, containing the
foodstuff, [0015] characterised in that the polyolefin-based film,
in particular the film based on biaxially oriented polypropylene
(boPP) films, comprises at least one coating comprising (i)
acrylate polymer and/or (ii) halogen-containing vinyl polymers
and/or vinylidene polymers and/or (iii) polymers based on vinyl
alcohol (VOH), and this coating is present on the side of the film
facing towards the cardboard based on recycled cardboard.
[0016] The foodstuffs packaging according to the invention does not
require any barrier layers produced by metallisation of surfaces
and can thus be produced more economically than a metallised
cardboard or a metallised film, for example. In addition, with use
of transparent embodiments, the invention enables new types of
packaging that previously were not possible on account of the
metallisation.
A BRIEF DESCRIPTION OF THE FIGURE
[0017] FIG. 1 illustrates a test structure containing cardboard
saturated with a defined quantity of mineral oil which was covered
with the sample to be measured, Tenax.RTM. was distributed
thereon.
[0018] The invention can be provided by differently designed
foodstuffs packagings. In one embodiment bag packaging or wrap
packaging is produced with technology known per se and contains the
foodstuff. The filled bag or wrap packaging is then packaged in a
further encasing cardboard packaging. The coating on the outer side
of the bag or wrap packaging prevents the migration of the mineral
oils from the cardboard into the foodstuff. In a further embodiment
the cardboard can be laminated or lined with the coated film. A
packaging that contains the foodstuff is then produced from the
coated cardboard. This variant is advantageous for packaging in
which the foodstuff would otherwise come into direct contact with
the cardboard.
Film
[0019] The polyolefin-based films used within the scope of the
present invention are in particular films based on biaxially
oriented polypropylene (boPP) films. These films can be constructed
in a monolayer or multi-layer manner and have a coating comprising
(i) acrylate polymer and/or (ii) halogen-containing vinyl polymers
and/or vinylidene polymers and/or (iii) polymers based on vinyl
alcohol (VOH).
[0020] The monolayer film or the base layer of the multilayer film
contains polyolefin, preferably a propylene polymer and optionally
further conventional additives in effective quantities in each
case. The base layer generally contains at least 70 to <100% by
weight, preferably 75 to 98% by weight, in particular 85 to 95% by
weight, of the polyolefin, in each case in relation to the weight
of the layer.
[0021] Propylene polymers are preferred as polyolefins of the base
layer or as material for monolayer films. These propylene polymers
contain 90 to 100% by weight, preferably 95 to 100% by weight, in
particular 98 to 100% by weight, of propylene units and have a
melting point of 120.degree. C. or above, preferably 150 to
170.degree. C., and generally a melt flow index from 1 to 10 g/10
min, preferably 2 to 8 g/10 min, at 230.degree. C. and a force of
21.6 N (DIN 53735). Isotactic propylene homopolymer with an atactic
proportion of 15% by weight and below, copolymers of ethylene and
propylene with an ethylene content of 5% by weight or below,
copolymers of propylene with C.sub.4-C.sub.8 olefins with an olefin
content of 5% by weight or below, and terpolymers of propylene,
ethylene and butylene with an ethylene content of 10% by weight or
below and with a butylene content of 15% by weight or below are
preferred propylene polymers for the base layer, wherein isotactic
propylene homopolymer is particularly preferred. The specified
percentages by weight relate in each case to the respective
polymers.
[0022] Furthermore, a mixture of the specified propylene
homopolymers and/or copolymers and/or terpolymers and other
polyolefins, in particular of monomers with 2 to 6 C atoms, is
suitable, wherein the mixture contains at least 50% by weight, in
particular at least 75% by weight, of propylene polymer. Suitable
other polyolefins in the polymer mixture are polyethylenes, in
particular HDPE, MDPE, LDPE, VLDPE and LLDPE, wherein the
proportion of each of these polyolefins does not exceed 15% by
weight in relation to the polymer mixture.
[0023] In an opaque embodiment the base layer of the film or the
monolayer film contains vacuole-initiating fillers in a quantity of
at most 30% by weight, preferably 5 to 25% by weight, in relation
to the weight of the opaque base layer.
[0024] Vacuole-initiating fillers are solid particles that are
incompatible with the polymer matrix and, as the films are
stretched, lead to the formation of vacuole-like cavities. The
vacuole-initiating fillers generally have a minimum size of 1 .mu.m
in order to lead to an effective, i.e. opaque-making, quantity of
vacuoles. The mean particle diameter of the particles is generally
1 to 6 .mu.m, preferably 1.5 to 5 .mu.m. The chemical nature of the
particles plays a subordinate role.
[0025] Conventional vacuole-initiating fillers are inorganic and/or
organic materials incompatible with polypropylene, such as
aluminium oxide, aluminium sulphate, barium sulphate, calcium
carbonate, magnesium carbonate, silicates such as aluminium
silicate (kaolin clay) and magnesium silicate (talc) and silicon
dioxide, from which calcium carbonate and silicon dioxide are
preferably used. The conventionally used polymers incompatible with
the polymers of the base layer are considered as organic fillers,
in particular copolymers of cyclic olefins (COC) as described in
EP-A-O 623 463, polyesters, polystyrenes, polyamides, halogenated
organic polymers, wherein polyesters such as polybutylene
terephthalates and cycloolefin copolymers are preferred.
Incompatible materials or incompatible polymers in the sense of the
present invention means that the material or the polymer is present
in the film in the form of separate particles or in the form of a
separate phase.
[0026] In a further opaque embodiment the base layer or the
monolayer films, additionally or alternatively to the
vacuole-initiating fillers, contain pigments, for example in a
quantity from 0.5 to 10% by weight, preferably 1 to 8% by weight,
in particular 1 to 5% by weight. The specified quantities relate to
the weight of the layer.
[0027] Pigments in the sense of the present invention are
incompatible particles that essentially do not lead to vacuole
formation as the film is stretched. The, for example, colouring
effect of the pigments is caused by the particles themselves.
Pigments are both what are known as "white pigments" which colour
the films white, and "coloured pigments" which provide the film
with a bright or black colour. Generally the mean particle diameter
of the pigments lies in the range from 0.01 to 1 .mu.m, preferably
0.01 to 0.7 .mu.m, in particular 0.01 to 0.4 .mu.m.
[0028] Conventional pigments are materials such as aluminium oxide,
aluminium sulphate, barium sulphate, calcium carbonate, magnesium
carbonate, silicates such as aluminium silicate (kaolin clay) and
magnesium silicate (talc), silicon dioxide and titanium dioxide,
from which white pigments such as calcium carbonate, silicon
dioxide, titanium dioxide and barium sulphate are preferably used.
Titanium dioxide is particularly preferred. Various modifications
and coatings of TiO.sub.2 are known per se in the prior art.
[0029] The density of the film is determined essentially by the
density of the base layer. The density of the base layer generally
lies in a range from 0.45-0.95 g/cm.sup.3. The vacuoles reduce the
density of the base layer, and pigments increase the density of the
base layer compared with the density of polypropylene (.about.0.9
g/cm.sup.3).
[0030] The thickness of the film lies generally in a range from 20
to 100 .mu.m, preferably 25 to 60 .mu.m, in particular 30 to 50
.mu.m. Insofar as the films have a multi-layered structure, the
thickness of the base layer is between 10 and 60 .mu.m, preferably
between 10 and 40 .mu.m. The above-mentioned thicknesses are to be
understood without the coating comprising (i) acrylate polymer
and/or (ii) halogen-containing vinyl and/or vinylidene polymers
and/or (iii) polymers based on vinyl alcohol (VOH).
[0031] Insofar as the film is multi-layered, the films also
comprise, besides the specified base layer, further layers that are
applied at least to one side or to both opposite sides of the base
layer. A three-layered structure of the film thus results in the
case of two cover layers.
[0032] The thickness of the cover layer is generally 0.5-3 .mu.m.
In a further embodiment of the invention intermediate layers are
also located on one or both sides between the cover layer and the
base layer, the thickness of said intermediate layers lying in the
range from 1 to 8 .mu.m. With a combination of intermediate layer
and cover layer, these together preferably have a total thickness
from 2 to 8 .mu.m.
[0033] The cover layers can be formed as a sealable layer, wherein
this is understood to mean both heat-sealable and cold-sealable
layers. Cold seal coatings can be applied directly to the surface
of a monolayer film. However, it is generally preferred to cover
the base layer first with a coextruded polymer layer and to apply
the cold seal coating to this polymer cover layer. Suitable
materials for the hot-sealable cover layer are the homopolymers,
copolymers and terpolymers specified hereinafter.
[0034] To improve the adhesion, the surface of the film is
subjected, prior to the coating in a manner known per se by means
of corona, flame or plasma, to a method in order to increase the
surface tension. The surface tension of the layer thus treated then
lies typically in a range from 35 to 45 mN/m. This surface
treatment can be performed on one or both surfaces of the film.
[0035] The above-described cover and intermediate layer generally
contain at least 80% by weight, preferably 90 to <100% by weight
of olefin polymers or mixtures thereof, and optionally also
conventional additives, in each case in effective quantities.
Suitable polyolefins are, for example, polyethylenes, propylene
copolymers and/or propylene terpolymers, and also the propylene
homopolymers already described in conjunction with the base
layer.
[0036] Suitable propylene copolymers or terpolymers are generally
constructed from at least 50% by weight of propylene units and
ethylene units and/or butylene units as comonomer. Preferred mixed
polymers are static ethylene-propylene copolymers with an ethylene
content from 2 to 10% by weight, preferably 5 to 8% by weight, or
static propylene-butylene-1 copolymers with a butylene content from
4 to 25% by weight, preferably 10 to 20% by weight, in each case in
relation to the total weight of the copolymer, or static
ethylene-propylene-butylene-1 terpolymers with an ethylene content
from 1 to 10% by weight, preferably 2 to 6% by weight, and a
butylene-1 content from 3 to 20% by weight, preferably 8 to 10% by
weight, in each case in relation to the total weight of the
terpolymer. These co- and terpolymers generally have a melt flow
index from 3 to 15 g/10 min, preferably 3 to 9 g/10 min
(230.degree. C., 21.6 N DIN 53735) and a melting point from 70 to
145.degree. C., preferably 90 to 140.degree. C. (DSC).
[0037] Suitable polyethylenes are, for example, HDPE, MDPE, LDPE,
LLDPE and VLDPE, from which HDPE and MDPE types are particularly
preferred. The HDPE generally has an MFI (50 N/190.degree. C.) of
greater than 0.1 to 50 g/10 min, preferably 0.6 to 20 g/10 min,
measured in accordance with DIN 53 735, and a viscosity number,
measured in accordance with DIN 53 728, part 4, or ISO 1191, in the
range from 100 to 450 cm.sup.3/g, preferably 120 to 280 cm.sup.3/g.
The crystallinity is 35 to 80%, preferably 50 to 80%. The density,
measured at 23.degree. C. in accordance with DIN 53 479, method A,
or ISO 1183, lies in the range from >0.94 to 0.96 g/cm.sup.3.
The melting point, measured with DSC (maximum of the melt curve,
heating rate 20.degree. C./min), lies between 120 and 140.degree.
C. Suitable MDPE generally has an MFI (50 N/190.degree. C.) of
greater than 0.1 to 50 g/10 min, preferably 0.6 to 20 g/10 min,
measured in accordance with DIN 53 735. The density, measured at
23.degree. C. in accordance with DIN 53 479, method A, or ISO 1183,
lies in the range from >0.925 to 0.94 g/cm.sup.3. The melting
point, measured with DSC (maximum of the melt curve, heating rate
20.degree. C./min), lies between 115 and 130.degree. C.
[0038] The film generally contains, in the respective layers,
conventional stabilisers and neutralising agents in conventional
quantities, and optionally antiblocking agents in the cover
layer(s). Only additives or quantities of additives that do not
impair the coatings are added as lubricants and antistatic agents
to the layers.
[0039] The conventional compounds having a stabilising effect for
ethylene, propylene and other olefin polymers can be used as
stabilisers. The added quantity of said compounds lies between 0.05
and 2% by weight. Phenolic stabilisers, alkali/alkaline earth
stearates and/or alkali/alkaline earth carbonates are particularly
suitable. Phenolic stabilisers are preferred in a quantity from 0.1
to 0.6% by weight, in particular 0.15 to 0.3% by weight, and with a
molar mass of more than 500 g/mol. Pentaerythrityl
tetrakis-3-(3,5-di-tertiary butyl-4-hydroxyphenyl)propionate or
1,3,5-trimethyl-2,4,6-tris(3,5-di-tertiary
butyl-4-hydroxybenzyl)benzene are particularly advantageous.
[0040] Neutralising agents are preferably calcium carbonate and/or
dihydrotalcite (DHT) of a mean particle size of at most 0.7 .mu.m,
an absolute particle size of less than 10 .mu.m, and a specific
surface area of at least 40 m.sup.2/g. Neutralising agents in a
quantity from 50 to 1000 ppm, in relation to the layer, are
generally used.
[0041] Suitable antiblocking agents are inorganic additives such as
silicon dioxide, calcium carbonate, magnesium silicate, aluminium
silicate, calcium phosphate and the like and/or incompatible
polymers, such as polymethyl methacrylate (PMMA) polyamides,
polyesters, polycarbonates and the like, preferably polymethyl
methacrylate (PMMA), silicon dioxide and calcium carbonate. The
effective quantity of antiblocking agent lies in the range from 0.1
to 2% by weight, preferably 0.1 to 0.5% by weight, in relation to
the respective cover layer. The mean particle size lies between 1
and 6 .mu.m, in particular 2 and 5 .mu.m, wherein particles with a
spherical form, as described in EP-A-0 236 945 and DE-A-38 01 535,
are particularly suitable.
[0042] The film provided in the packaging according to the
invention is produced by means of processes and methods known per
se.
[0043] In respect of the subsequent coating, the film should
generally have no migrating additives in any layer, for example
should comprise no lubricants or antistatic agents, since these may
lead to problems with regard to the adhesion of the coating.
Coating
[0044] The polyolefin-based films used within the scope of the
present invention, in particular the films based on biaxially
oriented polypropylene (boPP) films, have a coating comprising (i)
acrylate polymer and/or (ii) halogen-containing vinyl and/or
vinylidene polymers and/or (iii) polymers based on vinyl alcohol
(VOH). The coating may be present on one or both sides of the
film.
[0045] The total thickness of the coating per side of the film is
generally between 0.1-5 .mu.m, preferably between 0.5-3 .mu.m. The
coating may be applied in a multiple layers, wherein combinations
of different materials/polymers, for example acrylate polymer and
polyvinylidene dichloride (PVDC), are also used. In the present
case, multiple layers means that, per layer, one of the specified
materials selected from the group acrylate polymer, polyvinylidene
dichloride (PVDC) or polymers based on vinyl alcohol (VOH) is
present as primary component.
[0046] The film is generally treated initially on the side to be
coated so as to increase the surface tension. Once the surface
tension has been increased, an adhesion promoter is usually applied
to the surface to be coated. Such adhesion promoters are known per
se and are based for example on polyurethane, acrylate polymers or
polyethylene imines. The adhesion promoters can also be applied in
multiple layers (secondary adhesion promoter layer), wherein
combinations of different adhesion promoters are also possible. In
the present case, multiple layers means that, per layer, one of the
above-mentioned adhesion promoters is present as primary component.
If aqueous polyethylene imine solution is applied as adhesion
promoter, this usually contains 1% by weight of polyethylene imine.
Polyethylene imine solution promotes the subsequent coating, as
described in EP-A-0255870.
[0047] The coating materials according to the invention are (i)
acrylate polymer and/or (ii) halogen-containing vinyl polymers
and/or vinylidene polymers and/or (iii) polymers based on vinyl
alcohol (VOH). These are in each case arranged as a specific layer.
Specific layers are homogeneous layers made of a defined coating
material. Here, mixtures of the above-specified materials/polymers
are not desirable for the respective coating material, but are not
ruled out in the form of copolymers.
[0048] Besides the above-specified materials, the coatings possibly
also contain further components, for example as lubricants,
preferably non-migrating lubricants, such as waxes and/or
antiblocking agents.
[0049] The coating materials according to the invention are applied
as dispersions, in particular aqueous dispersions, of which the
solids content is between 10 to 70% by weight, preferably 20-60% by
weight.
[0050] The acrylate polymers used in accordance with the invention
are preferably acrylate homopolymers and/or acrylate copolymers
based on, for example, alkyl acrylates, such as methyl methacrylate
and/or ethyl acrylate, or further comonomers, such as unsaturated
carboxylic acids or substituted vinyl compounds. An acrylate
copolymer can be constructed from 2 or more different monomers.
Furthermore, mixtures of the respective acrylate homopolymers
and/or acrylate copolymers are possible. Materials of this type are
obtainable on the market for example under the name NeoCryl BT-36
and NeoCryl FL-711 from the company DSM NeoResins (Netherlands) or
under another name from the company BASF. Preferred aqueous coating
dispersions based on acrylate polymer comprise at least 80% by
weight acrylate dispersion, at least 10% by weight wax dispersion,
at least 12% by weight dispersion of a colloidal silica, and at
least 7% by weight of antiblocking agent dispersion. The
differences to make up 100% by weight consist of water. The
quantity of acrylate coating per side of the film after drying is
generally between 0.1 and 1.5 g/m.sup.2. The thickness of this
acrylate layer is <2.0 .mu.m, inclusive of the layer of the
adhesion promoter.
[0051] The halogen-containing vinyl polymers and/or vinylidene
polymers used in accordance with the invention are preferably
polymers based on vinyl chloride homopolymers and/or vinylidene
chloride homopolymers and/or copolymers, wherein the comonomer
originates from the group of vinyl acetates, vinyl halides or
acrylates. The individual monomers can be present in different
weighting in the copolymer. Such materials are obtainable on the
market for example under the name Diofan.RTM. A 297, Diofan.RTM. A
114 and Diofan.RTM. B 200 from the company SolVin.S.A. (Belgium).
Preferred aqueous coating dispersions based on halogen-containing
vinyl polymers and/or vinylidene polymers, in particular
polyvinylidene dichloride (PVDC), comprise at least 95% by weight
of PVDC acrylate copolymer dispersion, at least 10% by weight of
wax dispersion, at least 7% by weight of antiblock dispersion. The
differences to make up 100% by weight consist of water. The
quantity of coating per side of the film after drying is generally
between 2.5 and 4 g/m.sup.2. The thickness of this layer is <4.5
.mu.m, inclusive of the layer of the adhesion promoter.
[0052] The polymers based on vinyl alcohol (VOH) used in accordance
with the invention are vinyl polymers that are known per se.
Preferred aqueous coating materials based on vinyl alcohol (VOH)
are ethylene vinyl alcohol (EVOH) and comprise 5-15% by weight of a
mixture of ethylene vinyl alcohol and polyvinyl alcohol, preferably
in the ratio 0.8-1.2 to 1.2-0.8, in particular 1:1 ratios by
weight. The quantity of coating per side of the film after drying
is generally between 0.5 and 1.0 g/m.sup.2 for coating materials
based on vinyl alcohol (VOH). The thickness of this layer is
<2.0 .mu.m, inclusive of the layer of the adhesion promoter.
[0053] The coating materials according to the invention are applied
preferably after the increase of the surface tension, for example
by corona treatment, whereby the adhesion is improved. As already
mentioned, an adhesion promoter is usually applied to the side to
be coated following the surface treatment and is dried. Insofar as
a secondary adhesion promoter (second adhesion promoter layer) is
advantageous, this is also applied. The adhesion promoter and the
coating materials are applied in accordance with methods known per
se, such as roller coating (roll application systems, for example
with engraved rolls), curtain coating, spray coating. The applied
coating is then dried using conventional drying methods (for
example hot air).
[0054] The coated films are used in accordance with the invention
such that the coated side of the film faces towards the loaded
cardboard. Surprisingly, the coating in direct contact with the
loaded cardboard constitutes an effective migration barrier. Thus,
the alternative metallisation of the film or of the cardboard can
be omitted. The packaging according to the invention is therefore
preferably free from an additional metal layer. This, however, does
not rule out metallic prints or similar metallic decorations.
Cost-efficient packaging made of loaded cardboard packaging can
thus be produced, with which no considerable quantities or even no
quantity of mineral oils migrate into the foodstuff.
DEFINITION OF RECYCLED CARDBOARD
[0055] The cardboard based on recycled cardboard used within the
scope of the present invention is constituted by cardboard
packaging that comprises significant quantities of mineral oils and
is thus subject to the provisions of COMMISSION REGULATION (EC) no.
1935/2004 of 27 Oct. 2004 (also referred to hereinafter or below as
loaded cardboard packaging).
[0056] Cardboard packaging of this type based on recycled cardboard
typically contains at least 300-1000 mg/kg mineral oil. These
mineral oils are referred to as "mineral oil saturated
hydrocarbons" (MOSH) or as "mineral oil aromatic hydrocarbons"
(MOAH). The MOSH and MOAH mineral oils are often also specified in
terms of their carbon chains, for example as MOSH 14-24, MOSH
24-35, MOAH 14-24 and MOAH 24-35, wherein the numerical value
reflects the number of carbon atoms. The exact composition of the
MOSH and MOAH mineral oils is dependent on the type of recycled
cardboard, i.e. the fractions of MOSH 14-24, MOSH 24-35, MOAH 14-24
and MOAH 24-35 are different.
[0057] The film provided in the foodstuffs packaging according to
the invention has good barrier properties with respect to MOSH and
MOAH mineral oils, in particular with respect to MOSH 14-24, MOSH
24-35, MOAH 14-24 and MOAH 24-35.
[0058] The film provided in the foodstuffs packaging according to
the invention preferably has a good barrier to MOSH and MOAH
mineral oils, such that it may come into contact with foodstuffs in
accordance with COMMISSION REGULATION (EC) no. 1935/2004 of 27 Oct.
2004. A foodstuff simulant, i.e. a test medium, that mimics dry
foodstuffs pursuant to COMMISSION REGULATION (EC) no. 10/2011 of 14
Jan. 2011 is understood to be a foodstuff. The behaviour of this
foodstuff simulant mimics the migration from foodstuff contact
materials.
[0059] With the use according to the invention of the coated film
in the foodstuffs packaging according to the invention, merely at
most 1%, in particular at most 0.5%, of the MOSH 14-24 fraction
present in the recycled cardboard preferably migrates into a
foodstuff simulant pursuant to COMMISSION REGULATION (EC) no.
10/2011 of 14 Jan. 2011 (Tenax.RTM. obtainable from the company
Buchem B.V, poly(2,6-diphenyl-p-phenylene oxide), particle size
60-80 mesh, pore size 200 nm), when the recycled cardboard
comprises at least 300-1000 mg/kg mineral oil (sum of MOSH 14-24,
MOSH 24-35, MOAH 14-24 and MOAH 24-35) and the proportion of the
fraction MOSH 14-24 in the mineral oil is at least 30% by weight.
The above migration measurement is taken at 40.degree. C. and for
the duration of 10 days.
[0060] With the use according to the invention of the coated film
in the foodstuffs packaging according to the invention, merely at
most 1.6%, in particular at most 1.4%, of the MOSH 24-35 fraction
present in the recycled cardboard preferably migrate into a
foodstuff simulant pursuant to COMMISSION REGULATION (EC) no.
10/2011 of 14 Jan. 2011 (Tenax.RTM. obtainable from the company
Buchem B.V, poly(2,6-diphenyl-p-phenylene oxide), particle size
60-80 mesh, pore size 200 nm), when the recycled cardboard
comprises at least 300-1000 mg/kg mineral oil (sum of MOSH 14-24,
MOSH 24-35, MOAH 14-24 and MOAH 24-35) and the proportion of the
fraction MOSH 24-35 in the mineral oil is at least 10% by weight.
The above migration measurement is taken at 40.degree. C. and for
the duration of 10 days.
[0061] With the use according to the invention of the coated film
in the foodstuffs packaging according to the invention, merely at
most 0.5%, in particular at most 0.3%, of the MOAH 14-24 fraction
present in the recycled cardboard preferably migrates into a
foodstuff simulant pursuant to COMMISSION REGULATION (EC) no.
10/2011 of 14 Jan. 2011 (Tenax.RTM. obtainable from the company
Buchem B.V, poly(2,6-diphenyl-p-phenylene oxide), particle size
60-80 mesh, pore size 200 nm), when the recycled cardboard
comprises at least 300-1000 mg/kg mineral oil (sum of MOSH 14-24,
MOSH 24-35, MOAH 14-24 and MOAH 24-35) and the proportion of the
fraction MOAH 14-24 in the mineral oil is at least 10% by weight.
The above migration measurement is taken at 40.degree. C. and for
the duration of 10 days.
[0062] With the use according to the invention of the coated film
in the foodstuffs packaging according to the invention, merely at
most 3.5%, in particular at most 2.0%, particularly preferably at
most 1.0%, of the MOAH 24-35 fraction present in the recycled
cardboard preferably migrate into a foodstuff simulant pursuant to
COMMISSION REGULATION (EC) no. 10/2011 of 14 Jan. 2011 (Tenax.RTM.
obtainable from the company Buchem B.V,
poly(2,6-diphenyl-p-phenylene oxide), particle size 60-mesh, pore
size 200 nm), when the recycled cardboard comprises at least
300-1000 mg/kg mineral oil (sum of MOSH 14-24, MOSH 24-35, MOAH
14-24 and MOAH 24-35) and the proportion of the fraction MOAH 24-35
in the mineral oil is at least 1% by weight. The above migration
measurement is taken at 40.degree. C. and for the duration of 10
days.
[0063] The present invention also relates to the use of the film
described in the introduction for the production of foodstuffs
packaging comprising recycled cardboard.
[0064] The film contained in the foodstuffs packaging according to
the invention is produced by means of extrusion or coextrusion
methods known per se, wherein the stenter method is preferred in
particular.
[0065] To this end, the melts corresponding to the individual
layers of the film are coextruded through a flat film die, the film
thus obtained is removed for solidification on one or more roll(s),
the film is then stretched (oriented), the stretched film is then
heat set and optionally plasma-, corona- or flame-treated at the
surface layer intended for treatment.
[0066] More specifically, as in the extrusion method, the polymers
or the polymer mixture of the individual layers is/are compressed
here in an extruder and liquefied, wherein optionally added
additives may already be contained in the polymer or in the polymer
mixture. Alternatively, these additives can also be incorporated
via a master batch.
[0067] The melts are then optionally pressed jointly and
simultaneously through a flat film die (slit die), and the pressed
multilayer film is removed on one or more take-off rolls at a
temperature from 5 to 100.degree. C., preferably 10 to 50.degree.
C., wherein said film cools and solidifies.
[0068] The film thus obtained is then stretched longitudinally and
transversely to the extrusion direction, which leads to an
orientation of the molecule chains. The longitudinal stretching is
preferably performed at a temperature from 80 to 150.degree. C.,
expediently with the aid of two rolls running at different speeds
in accordance with the sought draw ratio, and the transverse
stretching is preferably performed at a temperature from 120 to
170.degree. C. with the aid of an appropriate clip frame. The
longitudinal draw ratios lie in the range from 4 to 8, preferably
4.5 to 6. The transverse draw ratios lie in the range from 5 to 10,
preferably 7 to 9.
[0069] The stretching of the film is followed by the heat setting
of said film (heat treatment), wherein the film is held for
approximately 0.1 to 10 s long at a temperature from 100 to
160.degree. C. The film is then usually rolled up using a winding
device.
[0070] Following the biaxial stretching, one or both surface/s of
the film is/are preferably plasma-, corona- or flame-treated in
accordance with one of the known methods. The treatment intensity
generally lies in the range from 35 to 45 mN/m, preferably 37 to 45
mN/m, in particular 38 to 41 mN/m.
[0071] For the alternative corona treatment the film is passed
through between two conductor elements serving as electrodes,
wherein a sufficiently high voltage, usually an AC voltage
(approximately 10,000 V and 10,000 Hz), is applied between the
electrodes so that spray or corona discharges can take place. Due
to the spray or corona discharge, the air above the film surface is
ionised and reacts with the molecules of the film surface, such
that polar deposits in the essentially unipolar polymer matrix are
produced. The treatment intensities lie within the conventional
scope, wherein 37 to 45 mN/m are preferred.
[0072] The coextruded multi-layer film is then provided on one or
both sides on one or both outer surface(s) with the above-described
coatings in accordance with the methods known per se.
[0073] To characterise the raw materials and the films, the
following measurement methods were used:
Melt Flow Index
[0074] The melt flow index was measured in accordance with DIN 53
735 and 21.6 N load and 230.degree. C.
Determination of the Ethylene Content
[0075] The ethylene content of the polyolefin copolymers was
determined by means of 13C-NMR spectroscopy. The measurements were
taken using a nuclear magnetic resonance spectrometer from the
company Bruker Avance 360. The copolymer to be characterised was
dissolved in tetrachloroethane, such that a 10% mixture was
produced. Octamethyltetrasiloxane (OTMS) was added as reference
standard. The nuclear magnetic resonance spectrum was measured at
120.degree. C. The spectra were evaluated as described in J.C.
Randall Polymer Sequence Distribution (Academic Press, New York,
1977).
Melting Point and Melt Enthalpy
[0076] The melting point and the melt enthalpy were determined by
means of a DSC (differential scanning calometry) measurement (DIN
51 007 and DIN 53 765). A few milligrams (3 to 5 mg) of the raw
material to be characterised were heated in a differential
calorimeter with a heating rate of 20.degree. C. per minute. The
heat flow rate was plotted against the temperature and the melting
point was determined as maximum of the melt curve, and the melt
enthalpy was determined as the area of the respective melt
peak.
Density
[0077] The density was determined in accordance with DIN 53 479,
method A.
Surface Tension
[0078] The surface tension was determined by means of ink methods
in accordance with DIN 53 364.
Friction
[0079] The friction was measured in accordance with DIN 533375.
Migration Measurement
[0080] The migration of the MOSH and MOAH mineral oils was measured
in accordance with the method developed by the BfR (Federal
Institute for Risk Assessment) in collaboration with the Kantonalen
Labor, Zurich. It was based on an analysis by means of gas
chromatography of the mineral oils following manual pre-separation
by column chromatography ("determination of hydrocarbons from
mineral oil (MOSH and MOAH) or plastics (POAH, PAO) in packaging
materials and dry foodstuffs by means of solid phase extraction and
GC-FID"). The method was presented at the conference "Mineral oils
in Foodstuffs Packaging--Development and Solution Approaches",
which took place on 22 and 23 Sep. 2011 in Berlin. A test substance
Tenax.RTM. obtainable from the company Buchem B.V
(poly(2,6-diphenyl-p-phenylene oxide), particle size 60-80 mesh,
pore size 200 nm) was used as foodstuff simulant.
[0081] Test structure (FIG. 1): A cardboard saturated with a
defined quantity of mineral oil was covered with the sample to be
measured, Tenax.RTM. was distributed thereon, and the entire
assembly was stored in a closed system made of aluminium
(temperature 40.degree. C., time 10 days).
[0082] Following the storage time, the Tenax.RTM. was extracted
with hexane and suitable internal standards were added (solid phase
extraction), then a separation was performed by means of liquid
chromatography (LC) with a stationary phase made of silica gel
doped with 0.3% silver nitrate and a mobile phase initially of
hexane, then a mixture of hexane, dichloromethane and toluene. The
eluate was separated in a third step by means of gas
chromatography, and detection was performed in a manner deviating
from the above-cited BfR method by means of GC-MS/FID.
[0083] The invention will now be explained by the following
examples.
Production of the Uncoated Films
[0084] The films type 1 to 3 were produced in accordance with the
known coextrusion method. Here, a transparent three-layered film
with cover layers on either side and with a total thickness of 25
.mu.m was produced by coextrusion and subsequent stepwise
orientation in the longitudinal and transverse direction. The cover
layers each had a thickness of 0.9 .mu.m.
TABLE-US-00001 FILM TYPE 1: Base layer: Approx. 100% by weight
isotactic propylene homopolymer with a melting point of 163.degree.
C. and a melt flow index of 3.2 g/10 min. Cover layers: Approx.
100% by weight static ethylene-propylene-butylene terpolymer with
an ethylene content of 3% by weight and a butylene content of 6% by
weight (rest propylene). 0.1% by weight SiO.sub.2 as antiblocking
agent with a mean particle size d.sub.50 of 5 .mu.m
[0085] The production conditions in the individual method steps
were:
TABLE-US-00002 Extrusion: Temperatures Base layer: 260.degree. C.
Cover layers: 240.degree. C. Temperature of the 30.degree. C.
take-off roll: Longitudinal Temperature: 120.degree. C. stretching:
Longitudinal draw ratio: 5.5 Transverse Temperature: 160.degree. C.
stretching: Transverse draw ratio: 9 Fixing: Temperature:
130.degree. C. Convergence 20%
[0086] All layers of the film contained neutralising agents and
stabilisers in the conventional quantities. Both surfaces were
pre-treated by means of corona in order to increase the surface
tension.
Film Type 2
[0087] A film was produced in accordance with film type 1. In
contrast to film type 1, both cover layers contained a static
ethylene-propylene copolymer with an ethylene content of approx.
4.5% by weight and a softening point of approx. 130.degree. C.
Film Type 3
Comparative Example
[0088] A film was produced in accordance with film type 1. In
contrast to film type 1, the base layer additionally contained
erucic acid amide as lubricant in a quantity of 0.05% by weight and
a bis-ethoxylated amine in a quantity of 0.09% by weight.
Coating
[0089] A polyethylene imine adhesion promoter was first applied to
the above-described uncoated film and then dried. Different
coatings made of acrylate polymer, PVDC or vinyl alcohol polymer
were then applied by means of engraving rolls.
EXAMPLE 1
[0090] A 1% by weight polyethylene imine dispersion was applied on
either side to film type 1 and was dried. An acrylate polymer
dispersion from the company NeoResins with trade name BT36 with a
solids content of 20% by weight was then applied likewise on either
side and was dried. Besides the acrylate polymer dispersion,
additives such as Carnauba wax and antiblocking agent were used.
The quantity was selected such that sufficient antiblock effect for
unwinding the film roll and also a frictional value of
approximately 0.3 were achieved.
[0091] The thickness of the acrylate polymer layer was 0.8 .mu.m,
which corresponded to a coating weight of 0.8 g/m.sup.2.
EXAMPLE 2
[0092] A film as described in Example 1 was produced. In contrast
to Example 1, however, only side 1 of film type 1 was coated with
the acrylate polymer dispersion. Side 2 was coated on the adhesion
promoter layer with a polyvinyl chloride dispersion from the
company Solvin with the trade name Diofan A114 having a solids
content of 50% by weight. Similarly to Example 1, additives
(Carnauba wax and antiblock) were also added here to both sides.
The thickness of the polyvinyl chloride layer was 2.0 .mu.m, which
corresponded to a coating weight of 3.5 g/m.sup.2.
EXAMPLE 3
[0093] A 1% by weight polyethylene imine dispersion was applied to
film type 2 on side 1 and was dried. A vinyl alcohol dispersion
from the company Kurary with the trade name Mowiol 3-98 and Exceval
AQ-4005 (in the ratio 1:1) having a solids content of, on the
whole, 10% by weight was applied thereto and dried.
[0094] The thickness of the coating layer was 0.8 .mu.m, which
corresponded to a coating weight of 0.8 g/m.sup.2. In addition,
additives such as Carnauba wax and antiblocking agent were used.
The quantity was selected such that sufficient antiblock effect for
unwinding the film roll and also a frictional value of
approximately 0.3 were achieved.
EXAMPLE 4
[0095] A film was produced in accordance with Example 3. In
contrast to Example 3, a 1% by weight polyethylene imine dispersion
was additionally applied to side 2 and was dried. An acrylate
polymer dispersion from the company NeoResins with the trade name
BT36, having a solids content of 20% by weight was applied to this
adhesion promoter layer and dried. Besides the acrylate polymer
dispersion, additives such as Carnauba wax and antiblocking agent
were used. The quantity was selected such that sufficient antiblock
effect for unwinding the film roll and also a frictional value of
approximately 0.3 were achieved. The thickness of the acrylate
polymer layer was 0.8 .mu.m, which corresponded to a coating weight
of 0.8 g/m.sup.2.
Comparative Example
[0096] Film type 3 was used without coating.
[0097] The above coating was varied in accordance with the
invention and is summarised in Table 1:
TABLE-US-00003 Coating Mineral oil barrier Front side = +++ very
good side 1 Coating ++ good (facing towards Rear side = +
satisfactory the cardboard) side 2 - no barrier Example 1 Acrylate
polymer Acrylate polymer MOSH 14-24 +++ (film type 1: 0.8 .mu.m
coating 0.8 .mu.m coating MOSH 24-35 ++ terpo-homo- layer thickness
layer thickness MOAH 14-24 +++ terpo) MOAH 24-35 +++ Example 2
Acrylate polymer PVDC MOSH 14-24 ++ (film type 1: 0.8 .mu.m coating
2.0 .mu.m coating MOSH 24-35 ++ terpo-homo- layer thickness layer
thickness MOAH 14-24 +++ terpo) MOAH 24-35 +++ Example 3 Vinyl
alcohol none MOSH 14-24 ++ (film type 2: polymer (EVOH) MOSH 24-35
+ Copo-homo- 0.8 .mu.m coating MOAH 14-24 +++ Copo) layer thickness
MOAH 24-35 +/- Example 4 Vinyl alcohol Acrylate polymer MOSH 14-24
+++ (film type 2: polymer (EVOH) 0.8 .mu.m coating MOSH 24-35 ++
Copo-homo- 0.8 .mu.m coating layer thickness MOAH 14-24 +++ Copo)
layer thickness MOAH 24-35 ++ Comparative none none MOSH 14-24 -
example 1 MOSH 24-35 - (film type 3) MOAH 14-24 - MOAH 24-35 -
* * * * *