comparison evoh pvdc draft pdw august 2012 v1
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1 © 2012 Solvay Specialty Polymers
Competitive advantage PVDC vs EVOH
EVOH Applications is larger : Bottles, Rigid pack, Flexible films (Shrink or No shrink films), Cosmetic , Automotive Tank, heating pipe,..
PVDC Resins applications is mainly: Flexible shrink films Worldwide volume of barrier film resin used in shrink film
Total 25.150 MT, PVDC 84 % - EVOH 16 % (2010)Advantages Disavantages
Barrier EVOH has a superior gas barrier when exposed to low moisture conditions
EVOH has a poor WVTr barrier
PVDC has a very good gas barrier and Not affected by moisture conditionsPVDC has excellent moisture (WVtr) barrierAt low temperature (4°C) the PVDC has a better Oxygen barrierPVDC performs well in retort process EVOH looses barrier level after retort
Process EVOH is reasonable easy to process. EVOH is hydroscopic, that can impact both the processability and end use of EVOH
EVOH can be coextruded with many different polymers in coextrusion process
Some grades of EVOH can be difficult to process (low PE content high barrier))
PVDC : new extrusion technologies has been developed in which PVDC is coextruded with many different polymers
PVDC is very heat sensitive, which makes it difficult to process. Special alloys necessary to process PVDC
Shrinkage Bioriented Film PVDC can reach 50 and more % of shrink in the both direction, without delamination problem
EVOH is limited in shrink ratio (bioriented film)
Recycle EVOH regrind can be reused PVDC is more difficult to reused (solutions exist)
2 © 2012 Solvay Specialty Polymers
Competitive advantage PVDC vs EVOH
Permeability of various polymers mainly in food packaging*
EVOH (EVAL)
PVOH (PVAL)
Water vapour
38°C/ 90% RHg•µm/(m²•d)
Oxygen Dry: 23°C/ 0% RHcm³•µm/(m²•d•atm)
0
0
LDPE
HDPE
OPP
R-PVC
PA 6-6
PETP
PAN
Cellophane
ca. 200,000
ca. 60,000
ca. 50,000
2500 – 3000
1600 – 2500
ca. 1500
100 – 300
5 – 80
300 – 500
3 – 4 > 500,000
ca. 100,000
1500 – 3500
1500 – 2000
ca. 800
1000 – 2000
600 – 900
100 – 200
ca. 150
300 – 500
PVdC 8 – 230 6 – 80
* Film thickness: 1 µm (intrinsic permeability)
Barrier for Oxygen and Water vapourBarrier for Oxygen and Water vapour
3 © 2012 Solvay Specialty Polymers
Competitive advantage PVDC vs EVOH
PE
EV
AB
arri
er
lay
er 9
0% R
HE
VA
PE
PVdC Coatin
gsPVdC E
xtrusio
n
100%
Relative Humidity
10
100
1000
0% 20% 40% 60% 80%
OT
R a
t 20
°C,
cm³·
µm
/m2 ·
d·a
tm)
EVOH (29%mol. C2H4)
EVOH (32%mol. C2H4)
EVOH (44%mol. C2H4)
N-MXD6 (bioriented film)
N-MXD6 (cast film)
[Data Sources: SolVin, Datasheet Nippon-Goshei]
PVDC: a reliable barrier in humid conditionsPVDC: a reliable barrier in humid conditions
100% RHInside
packaging
80% RHOutside
packaging
0.0025
4 © 2012 Solvay Specialty Polymers
Comparison EVOH and PVDC Barrier filmsprog 6477 : Optical microscopy
1 A (6477/2) PVDC 3 A ( 6477 / 4) EVOH4 layers : 7 / 10 / 7 / 40 µm 8 layers : 3 / 2 / 19 / 2 / 4 / 2 / 3 / 14EVA / EVA / Copo VDC-MA / EVA PET / PE / PE / PE / PA / EVOH / PA / PE
2 A (6477/3) PVDC 4 A (6477/4) EVOH5 layers : 10 / 6 /10 / 14 / 15 µm 4 or 5 layers : 7 / 6 / 5 / 4 / 22 (layer 1 and 2 perhaps 1 layer)PE / EVA / Copo VDC-MA / EVA / PE PA / PA / EVOH / PE / PE
Oxygen Barrier 5mocon Oxtram 2/2023°C 23°C 11°C 5 °C (*)
85 % RH 0% RH 0% RH 0 % RHPVDC 1 7 7 2 0,9PVDC 2 11 11 3 1,5EVOH 1 6 7 3 2EVOH 2 16 10 5 2,5(*) external measurement
Barrier properties PVDC and EVOH/PA Films
0
2
4
6
8
10
12
0 5 10 15 20 25
Temperature, °C
OT
R, 0
% R
H, c
c/m
² d
b
PVDC1
PVDC2
EVOH 1
EVOH2
5 © 2012 Solvay Specialty Polymers
Typical shrink curve
High shrink (up to 60 %) Homogeneous in both directions
Tight vacuum packaging
Shrink (%) versus Temperature (°C)
0
10
20
30
40
50
60
70
60 65 70 75 80 85 90 95 100 105 110
Temperature (°C)
Sh
rin
k (%
)
longitudinaltransversal
6 © 2012 Solvay Specialty Polymers
Thickness and barrier integrity after shrink
50 % shrink in both directions: PVDC thickness ©: 8 µm 32 µm Homogeneous thickness distribution preserved after shrink Intrinsic barrier maintained after shrink
OTR at 25 °C, 85 % RH: 6.2 cc/m².d.bar 1.5 cc/m².d.bar Normalised for 1 µm: constant at 48 cc.µm/m².d.bar
100 °C1 s
50 % shrink
A
B
C E
D
A
BC
E
D
Microtome cut before shrink (scale = 20 µm)
Microtome cut after shrink (scale = 50 µm)
7 © 2012 Solvay Specialty Polymers
New extrusion technology for multilayer blown film (No shrink film)
Interest in multilayer blown films with PVDC has grown Can lead to a one-step process, eliminating laminations Use the advantages & benefits of PVDC for non-shrink applications
The challenge: Larger dies are used (>20 cm), which extend the residence time inside the die, and can accelerate degradation
2 concepts to overcome this: Pre-encapsulation of PVDC by another resin which is thermally
stable and compatible with PVDC. Macro Engineering Improved thermal insulation between layers Brampton Engineering
8 © 2012 Solvay Specialty Polymers
Pre-encapsulation technology
Objective: minimize contact of PVDC with metal surface in the adaptor and die by early encapsulation
“Early”: In the feed block before entering the die, or immediately after entering the die
“Encapsulation” with EVA or EMA EVA max use = 240-250°C EMA max use = 300°C EMA has higher polarity (better compatibility with PVDC)
Overlap in the die of about 10 cm Assure barrier layer
Results Extended run time Extended die life
Picture courtesy of Macro Engineering & Technology, Inc.
9 © 2012 Solvay Specialty Polymers
Exemple of structure PE done with Macro line
LLDPE + LD/TL / PVS 100+ encapsulation / TL / Elite + LDPE thickness 40 µm
Water vapor transmission rate 38°C (100 °F) and 90 % RH 3 g/m² / day 0,2 g/100 in²/day
Oxygen Transmission Rate 22°C (72°F) 0% RH 7 cm³/m² / day 0,5 cm³/100 in²/day
Carbon dioxide Transmission Rate 22°C (72°F) 0% RH 28 cm³/m² / day 1,8 cm³/100 in²/day
Nitrogen Transmission Rate 22°C (72°F) 0% RH 1 cm³/m² / day 0,1 cm³/100 in²/day
Air Transmission Rate 22°C (72°F) 0% RH 2 cm³/m² / day 0,1 cm³/100 in²/day
PVDC thickness 6 µm 0,2 mil
Ultimate Tensile Strength ASTM D882MD 27 MPa 3915 psiTD 20 MPa 2900 psi
Ultimate elongation ASTM D882MD 290 % 290 %TD 520 % 520 %
Metric value Imperial value
10 © 2012 Solvay Specialty Polymers
Process structures requiring high T difference (+100°C) by increased T insulation within the die
Proven coextrusion of PA 666 (skin layer) & PVDC; potential for PA 6 & PVDC
Thermoforming applications Stackable die
Easily extendable (inner outer)
Easy maintenance
Cross section of ISO-thermISO-therm Die, courtesy Brampton Engineering, Inc. Die, courtesy Brampton Engineering, Inc.
Improved thermal isolation
11 © 2012 Solvay Specialty Polymers
Barrier after Retort (No Shrink film) Brampton Line
Function Processing temperature Thicknessµm
PA 666 copolymer PA 6 and PA 6,6 (80/20) mechanical properties 245 - 250 °C 17reduced cristallisation puncture resistance (PA limited to skin layer)better transparency thermoformingbetter BURfrost line shifted
E MAH maleic anhydride reacts chemically with PA tie layer 215-225 °C 20E is miscible with LDPE
LDPE cost reduction 185 - 190 °C 24EVA tie layer 185-190 °C 19
PVDC barrier 160 °C 31EVA tie layer 185 - 190 °C 22
m LLDPE metalloscene LDPE sealing layer 215 - 225 °C 40clarity, low temperature seal(blending ionomer is also an option)
Total thickness (µm) 173OTR @ 25 °C 1,2 cc/m2.d.b (dry and humid 85 %)
0,7 cc/m2.d.b after sterilisation
similar film structure containing EVOH excellent OTR dry < 1 but increased > 10 cc/m2.d.b after sterilisation
Polymer
12 © 2012 Solvay Specialty Polymers
Exemple of structure LDPE done with Brampton line
ISO therm technology Brampton line trials and new resin development
6 layers : LDPE / EVA / EVA / IXAN Resin / EVA / LDPE 25 / 13 / 7 / 10 / 7 / 8 µm (Total 70 µm) Oxygen Barrier @ 23°C 85% RH 3,5 cc/m² d b
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