Transcript Structure film EVOH - Főoldal | Bag In Box

Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Barrier Films :
Co-extruded EVOH film
and
Polyester-Metallised
film
for Bag-In-Box
application
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Structure of EVOH
Poly Ethylene (PE)
Poly Vinyl Alcohol (PVA)
Extrudability
Gas Barrier
( CH2
( CH2 CH )n
CH2 )m
OH
( CH2
CH2 )m ( CH2 CH )n
OH
Ethylene Vinyl Alcohol Copolymer (EVOH)
:C
:O
:H
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Coextruded EVOH Film Manufacture
Reels of coextruded film
Binding
Bubble
(PE based)
agent
Polyethylene
EVOH
Polyethylene
Blowing
Heating
Polyethylene
EVOH
Binding agent (PE)
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Structure & Manufacture of Metallised Polyester (METPET)
- First Part: Metallization Reel of Polyester/polyethylene
Reel of Polyethylene
Metallised polyester
(Co-extruded film)
Cooling cylinder
Aluminium vaporization
under vacuum
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Smurfit Bag-in-Box
Comparison EVOH & METPET
Structure & Manufacture of Metallised Polyester (METPET)
-2nd Part: lamination
Reel of Polyester
Metallised Polyéthylène
Reel of Polyethylene Film
Adhesive agent
Reel of
Polyethylene
Metallised
Polyester Film
laminated with
Polyethylene
Film
Binding
Cylinder
Adhesive agent
Reel of
Polyethylene
film
Binding
Cylinder
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Smurfit Bag-in-Box
Comparison EVOH et METPET Films
• 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 together
with some adhesive: this operation is delicat and can be critical to the quality
of the film.
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Smurfit Bag-in-Box
Comparison EVOH et METPET Films
CHARACTERISTICS OF BARRIER FILMS FOR BAG IN BOX
Dynamic
perforation
resistance
Food contact
agreement
Oxygen
Barrier
Sealing
Properties
Flavour
Barrier
Temperature
Resistance
Elongation
Properties
Oxygen Barrier
after transport
Antistatic
Properties
Seal Strength
Multilayer
Sliperiness
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Mechanical characteristics
OTR cm3/m2/1 atm.(23°C, 75%HR)
Oxygen permeability
600
530
500
400
Elongation
300
%
200
7
100
0
3
1 1,2
1,5
0
No
transport
85
After 400 Gelboflexes
(= 400km)
METPET 82µ (32/12/38)
EVOH 80µ (6µ EVOH
32% ethylene)
0,8
0,7
0,6
0,5
daN/15mm 0,4
0,3
0,2
0,1
0
0,75
0,2
Bond Strength
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Smurfit Bag-in-Box
EVOH film is a ‘flexible’ film. All the elements of the structure are polyethylene
and 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 layer
in 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 the
barrier layer, the film is very resistant to the rigours of transportation and
the ‘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 years
of 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 give
an indication of how EVOH film compared to metallised polyester laminate
when subjected to flex-cracking.
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Influence of Gelbo Flexing on Oxygen Transmission Rate
O.T.R. cm³/m²/atmos/24hr
(23°C,75%RH)
4
3 ,5
3
M ET P ET
2 ,5
2
1,5
1
P E / T ie / E V O H / T ie / P E
0 ,5
0
0
10 0
200
300
400
500
N um be r o f G e lbo f le xe s
(100 Cycles = 80 km)
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Smurfit Bag-in-Box
Comparison 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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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Influence of different barrier Films on SO2 Levels
(No transport)
Red Wine With no Tranport
Total SO2
120
CE (EVOH) /L
80
CM(METAL)/L
60
Free SO2
CE(EVOH)/T
40
CM(METAL)/T
20
270
240
210
180
150
120
90
60
30
0
0
SO2 (mg/l)
100
Time (days)
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Influence of different barrier Films on SO2 Levels
(With transport)
120
100
80
SO2 Total
CE (EVOH)/L
CM(METAL)/L
60
CE( EVOH)/T
SO2 Libre
40
20
CM(METAL) /T
270
240
210
180
150
120
90
60
30
0
0
SO2 (mg/l)
Red Wine with transport
Time (days)
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Smurfit Bag-in-Box
Comparison of EVOH & PETMET Films
Various
• MET- PET:
1) Opacity/ metal aspect:
– can protect un-packed bag-inbox 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
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Smurfit Bag-in-Box
Comparison EVOH et METPET Films
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
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.
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