1
Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Barrier Films :
Co-extruded EVOH film and
Polyester-Metallised
film
for Bag-In-Box application
2
Structure of EVOH
Poly Ethylene (PE)
(CH2 CH2( )m )nCHCH2
OH
Ethylene Vinyl Alcohol Copolymer (EVOH)
Poly Vinyl Alcohol (PVA)
Extrudability Gas Barrier
: C
: O
: H
CH2 CH2( )m )nCHCH2
OH
(
Smurfit Bag-in-Box Comparison of EVOH & PETMET Films
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Coextruded EVOH Film Manufacture
Binding
(PE based) agent
Polyethylene
Polyethylene
EVOH
EVOH
Binding agent (PE)
Polyethylene
Bubble
Heating
Blowing
Reels of coextruded film
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Structure & Manufacture of Metallised Polyester (METPET)
- First Part: Metallization -
Aluminium vaporization
under vacuum
Cooling cylinder
Reel of Polyester/polyethylene
(Co-extruded film) Reel of Polyethylene Metallised polyester
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Comparison EVOH & METPETComparison EVOH & METPETSmurfit Bag-in-Box
Structure & Manufacture of Metallised Polyester (METPET)
-2nd Part: lamination
Adhesive agent
Adhesive agent
Binding Cylinder
Reel of Polyethylene Film
Reel of Polyethylene
Metallised Polyester Film laminated with Polyethylene
Film
Binding Cylinder
Reel of Polyethylene
film
Reel of Polyester Metallised Polyéthylène
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Comparison EVOH et METPET FilmsSmurfit Bag-in-Box
• EVOH Film is made through a co-extrusion process that links the polyethylene, the Tie Layer (modified PE) at the same time. This means that the polyethylene and EVOH are extruded simultaneously.Due to that, the cohesion of this two materials is excellent.
• Metallised Polyester Film is made by lamination, The process requires three stages. We need to get first three films made by extrusion (2 polyethylene films and the polyester film independently) Then we have the vacuum-metallization of the aluminium on the polyester layer. This operation is very delicate because a very poor layer of aluminium is deposing on the film. This thin deposit is very fragile and can break very easily. The last stage consists of laminating these tree layers by sticking them togetherwith some adhesive: this operation is delicat and can be critical to the quality of the film.
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CHARACTERISTICS OF BARRIER FILMS FOR BAG IN BOX
Dynamic Dynamic perforation perforation resistanceresistance
Food contact agreement
TemperatureTemperatureResistanceResistance
AntistaticAntistaticPropertiesProperties
ElongationElongationPropertiesProperties
MultilayerMultilayer
FlavourFlavourBarrierBarrier
Oxygen Barrier Oxygen Barrier after transportafter transport
Oxygen Oxygen BarrierBarrier
Comparison EVOH et METPET FilmsSmurfit Bag-in-Box
SliperinessSliperiness
Seal StrengthSeal Strength
SealingSealing
PropertiesProperties
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Oxygen permeability
1
3
1,2 1,5
0
7
OT
R c
m3/
m2/
1 at
m.(
23°C
, 75%
HR
)
METPET 82µ (32/12/38)
EVOH 80µ (6µ EVOH32% ethylene)
Mechanical characteristics
No
transport After 400 Gelboflexes
(= 400km)
85
530
0
100
200
300
400
500
600
Elongation %
0,2
0,75
00,10,20,30,40,50,60,70,8
daN/15mm
Bond Strength
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EVOH film is a ‘flexible’ film. All the elements of the structure are polyethyleneand all therefore are ‘soft’ when compared to polyester. In addition, the oxygen barrier of the film comes from an EVOH copolymer which is an extruded layerin the film, rather than a layer of metal randomly deposited onto a film.
As a result of the ‘flexibility’ of the film and the manufacturing process of thebarrier layer, the film is very resistant to the rigours of transportation andthe ‘flex-cracking’ of the film which can result. It is this ‘flex-cracking of film which at its worst leads to pinholing in the film and leakers.
Whilst the oxygen permeability rate of a piece of virgin EVOH may be slightly higher (say 1.2 cc compared to 1 cc/m²/day) than metallised polyester laminate,laboratory tests, pallet vibration tests, transportation tests and many yearsof experience show EVOH film to be more resistant to flex-cracking than metallised polyester laminate, particularly over long distances.
Attached are two charts showing the results of some laboratory work which givean indication of how EVOH film compared to metallised polyester laminate when subjected to flex-cracking.
Smurfit Bag-in-Box
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
0
0,5
1
1,5
2
2,5
3
3,5
4
0 100 200 300 400 500
Number of Gelboflexes
O.T
.R.
cm³/
m²/
atm
os/
24h
r (2
3°C
,75%
RH
)
METPET
PE / Tie / EVOH /Tie/ PE
Influence of Gelbo Flexing on Oxygen Transmission Rate
(100 Cycles = 80 km)
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Smurfit Bag-in-Box Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET Films
• The following curves show the results of a study made by the « Institut coopératif du vin de Montpellier » and the Institut Œnologique de Champagne.
• So2 Levels (Free & Total) has been analysed on bag-in-box made with the same inner ply, and a different outside linner (EVOH & PETMET) filled with red wine, either tranported or not.
• These analyses reflects the level of the wine oxydation.
• N.B.: You will notice that analyses made on transported are more heterogeneous due to mechanical alterations.
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Influence of different barrier Films on SO2 Levels
(No transport)
Red Wine With no Tranport
0
20
40
60
80
100
120
0 30 60 90 120
150
180
210
240
270
Time (days)
SO2
(mg/
l)
CE (EVOH) /L
CM(METAL)/L
CE(EVOH)/T
CM(METAL)/T
Free SO2
Total SO2
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
Influence of different barrier Films on SO2 Levels
(With transport)
SO2 Libre
SO2 Total
Red Wine with transport
0
20
40
60
80
100
120
0 30 60 90 120
150
180
210
240
270
Time (days)
SO
2 (m
g/l
) CE (EVOH)/L
CM(METAL)/L
CE( EVOH)/T
CM(METAL) /T
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Comparison of EVOH & PETMET FilmsComparison of EVOH & PETMET FilmsSmurfit Bag-in-Box
• MET- PET:
1) Opacity/ metal aspect:
– can protect un-packed bag-in-box from light
– Can « hide » the product inside the bag
– Can Give a « richer » aspect
2) Environment:
– Waste can be incinerated, but it should be done in a smokeless (toxic gazes) incinerator to ensure complete combustion
– Metal wastes in the ashes
• EVOH:
1) Transparency:
– No foreign body
– No trapped air
– Can check for discolouration and any quality defects in the product.
2) Environment:
– Waste can be incinerated (No toxic gaz emission
– No metal presence in the ashes
Various
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Comparison EVOH et METPET FilmsComparison EVOH et METPET FilmsSmurfit Bag-in-Box
N.B.:
Recent reports in the Danish Press has focus attention on the levels of Primary aromatic amines (PAAs) in multi-layer flexible laminates.
Aromatic amines (which seem to be linked to cancer) can be produced when any isocyanates (used in some Polyurethane based adhesive) react readily with moisture or any residual alcohol solvents from printing inks…
Sixth amendment (2001/62/EEC) to 90/128/EEC directive has introduced a limit of 20mg/kg foodsttuff for PAAs.
Polyurethane is never used in the process of co-extruded film (EVOH film)
Some laminating Processes are using adhesive with high levels of isocyanates.
Point on Primary aromatic amines
(New 20001/62/EG Amendment to the 90/128/EG Directive)
Our Films in contact with the products fulfill the actual EEC/FDA regulations