Barrier Enhancement of Flexible Laminates, Adhesion ......May 22, 2017 · PVdC PE PET PET Al met Adhesive Al met Adhesive PE PET Al met PVdC Adhesive PVdC Al met Adhesive PE PET

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1 Esra Kucukpinar – Fraunhofer IVV - Adhesion and Barrier Aspects in VIP Laminates - 17th TAPPI European PLACE Conference 2019 Porto - Session 15 - Paper 2

Barrier Enhancement of Flexible Laminates, Adhesion Aspects – Applications in VIPs

Presented by:

Esra KucukpinarNicola Brzoska

Fraunhofer Institute forProcess Engineering and Packaging

Freising, Germany

16TH TAPPI EUROPEAN PLACE CONFERENCE


Our Business Fields

Product Performance

Recycling and Environment

Packaging

Food

Processing Machinery

2


What is a VIP?

High barrier laminates for VIPs

Why do we need further barrier enhancement?

Application of barrier lacquers

Experimental results

Conclusions and outlook

Outline


va-Q-tec AG, Building in Munich, Annex 39ARCELIK A.S. (Beko Brand)

What is a VIP?

PU

VIP

EPS

GLASSFIBRE

3


What is a VIP?

Thermal Conductivity, [mW/mK]


What is a VIP?

a

Thermal Conductivity, [mW/mK]

4


High Barrier Laminates for VIPs (VIP envelopes)

Permeationthrough laminatesurface

Permeationthrough seals

Porous core material

Cross-sectional view - „cut“ VIP

Bi-laminate

Water vapour transmission rate (WVTR): ~ 0.02 g/(m2d) at 38oC and 90% RH

O2 permeability: < 0.005 cm3 / (m2dbar) at 23oC and 50%RH

PET (12 µm)

PET (12 µm)

PE

PET (12 µm)

Al met

Adhesive

Al met

Adhesive

Al met

Adhesive

EVOH(12 µm)

PE

PET (12 µm)

Al met

Adhesive

Adhesive

Al met

Tri-laminate


Production of VIP Envelopes

----------- 300 nm

Roll-to-Roll Barrier Layer via Physical Vapour Deposition – Thermal Evaporation

Al layer, 50 nm

5


Production of VIP Envelopes Roll-to-Roll Lamination / Lacquering in Clean Room Environment

Protection from dust particles Enclosed, filtered air Flow controller

Al layer

Adhesive


Measurement of Barrier PerformancePermeation Measurement Techniques and Conditions

Electrolysis cell

Sample

Carrier gas

DIN EN ISO 15106-3

Measurement limit: 5 × 10-5 g / (m2day)

Sample area: 50 cm2

Temperature: 40 oC, RH: 90%

Data recordingand analysis

Water Vapour Transmission Rate (WVTR): Mocon® AquatranTM Model 2

O2 Permeability: Mocon® Oxtran® Model 2/21

DIN 53 380, T3

Measurement limit: 5 × 10-3 cc(STP) / (m2daybar)

Sample area: ~ 50 cm2

Temperature: 23 oC, RH: 50%

6


PET (23 µm)

PET (23 µm)

High costs of tri-laminates, trend isbi-laminates for cost reduction

Possible with metalised EVOH, but expensive

Sensitive to humidity

Alternatives needed

Reduction of the number of Al metallizedfilms, while maintaining barrier performance

Long lifetime of 60 years for buildings

Stability towards water vapour

Application of barrier lacquers PE

PET (12 µm)

Al met

Adhesive

Al met

PVdC

Adhesive

Targeted Bi-Laminate Structures withbarrier lacquers

Why do We Need Further Barrier Enhancement?

Current Challenges and Trends: Targets:

PE

PET (12 µm)

Al met

Adhesive

Al met

PVdC

Adhesive

State-of-the-Art PET (12 µm)

PET (12 µm)

PE

PET (12 µm)

Al met

Adhesive

Al met

Adhesive

Al met

Adhesive

EVOH(12 µm)

PE

PET (12 µm)

Al met

Adhesive

Adhesive

Al met


Application of Barrier Lacquers

Barrier Performance of VariousPolymers, 100 µm, 23oC

Combination of Metallized Layerswith Barrier Lacquers

LacqueredlayerEVOH, 32%EVOH, 38%

PLA

EVOH, 44%

EVOH, 27%

PET

PE-HDPE-LD

PSPVC-PPP PC

PVC-U

PA 6

CellulosePVdC

PENPAN

BOPP

0,01

0,1

1

10

100

1000

10000

0,01 0,1 1 10 100 1000

Water Vapour Transmission Rate [g / (m2∙d)]23oC, 85% RH

Oxy

gen

Per

mea

bil

ity

[cm

³ (S

TP

) / (

m2 ∙

d∙b

ar)

]23

oC

, 50%

RH

Aluminium layer

PVdC-2 PVdC-1

7


, , , , , ,

Application of Barrier Lacquers – Barrier PerformanceTesting of PVdC Solubility – Hansen Solubility Parameters (HSPs)

Identification and selection of potential „green“ solvents for various PVdC copolymers byapplication of HSP concept

Calculation of the HSP distance betweenvarious solvents and already known referencesolvents (e.g. the recommended solvent-blend)

Sucessful replacement of Toluene:

(Hansen 2007, Steven Abbott 2018)


0.10

0.06

0.03

0.02 0.01 0.02 0.01 0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.12

WV

TR

[g

m-2

d-1

]38

°C /

90

% R

H

Application of Barrier Lacquers – Barrier PerformanceWet Chemical Application of PVdC on Metallized Layers

Screening of various PVdCformulations, selection of

green solvent type

MEK:Toluene(65:35)

MEK:Ethylacetate(60:40)

MEK:n-Butylacetate(60:40)

Cyclohexanone:Ethylacetate

(60:40)Unsuitable

solvent blend

> 2,0 gꞏm-2ꞏd-1

Barrier Improvement Factor up to 7

PET

Al met

PVdC (~ 2.5 µm)

PET

Al met

PVdC Solid content: 20%

PET

Al met

PVdC (~ 2.5 µm)

PET

Al met

PVdC (~ 2.5 µm)

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0.090.14

0.02 0.02 0.03 0.030.08 0.10

0.34

0.51

0.01 0,010.00

0.10

0.20

0.30

0.40

0.50

0.60

WV

TR

[g

m-2

d-1

] 38

°C /

90

% R

H

PET

Barrier Laminates PerformanceFace-to-Face, Back-to-Face Structures

Water vapour barrier for Face-to-Face laminates

degrades

PET

Al met

PET

Al met

PVdCPE

PET

PET

Al metAdhesiveAl met

Adhesive

PE

PET

Al metPVdC

AdhesivePVdCAl met

AdhesivePE

PET

PET

Al metPVdC

AdhesiveAl met

Adhesive

PE

PET

Al met

Adhesive

PET

Al metPVdC

Adhesive

Back-to-Face

Reference


0.090.14

0.02 0.02 0.03 0.030.08 0.10

0.34

0.51

0.01 0,010.00

0.10

0.20

0.30

0.40

0.50

0.60

OT

R [

cm3

m-2

d-1

bar

-1]

23°C

/ 50

% R

H 0.2100.240

0.013 0.006 0.007 < 0,005 < 0,005 < 0,005 < 0,0050.00

0.10

0.20

0.30

Barrier Laminates PerformanceFace-to-Face, Back-to-Face Structures

PET

Al met

PET

Al met

PVdCPE

PET

PET


Adhesive

PE

PET

PET

Al metPVdC

AdhesivePVdCAl met

AdhesivePE

PET

PET

Al metPVdC

AdhesiveAl met

Adhesive

PE

PET

Al met

Adhesive

PET

Al metPVdC

Adhesive

Reference

Oxygen barrier for Face-to-Face laminates

did not degrade

?Back-to-

Face

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Permeation Through Inorganic Barrier Layers Macrodefects

• Size: Nanometer up to micrometer; Localized positions

• Unhindered transport: Free diffusion (d), Knudsen diffusion, molecular flow (c)

Microdefects (Nanodefects)

• Size: Sub-nanometer up to nanometer; Quasi-homogeneously distributed

• Hindered transport: Surface diffusion (b), capillary condensation (a)

Left: Affinito, Hilliard, A New Class of Ultra-Barrier Materials, 47th Annual Technical Conference Proceedings SVC, 2004, 563-593Right: J. Fahlteich et al., Transparente Hochbarriereschichten auf flexiblen Substraten, Dissertation, Chemnitz, 2010

(b)(a) (c) (d)


Possible Reasons for Water Vapour Barrier Degradation

Adhesive lamination trials showed that the barrier properties deteriorate, if the laminates consisted of at least one PVdClayer in the middle between 2 Al-layers:

1) Interaction between PVdC layer and laminating adhesive

2) Heat stability of PVdC duringlamination

PET

PET

PVdC

PVdC

Adhesive

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Interface between laminating adhesiveand PVdC showed no visible interactionbetween both layers

Barrier performance of Back-to-Face (B2F) type of structures demonstratedcompatibility between the layersAluminium / PVdC / Adhesive

Adhesive is not the reason!

1) Interaction between PVdC Layer and Laminating Adhesive

Adhesive

PVdC

Silicon wafer

PET

Interface

Adhesive / PVdC



Prolonged exposure of PVdC to heat, if PVdC islocated in between two adjacent aluminumlayers, as in F2F-type of laminates

Heat stability of PVdC is known to get decreaseddue to the presence of metal ions, like Al3+

Initial dehydrochlorination of PVdC

Formation of hygroscopic Al-salts, which furtheraccelerate the dehydrochlorination of PVdC

Tendency of barrier loss increases when twolayers of PVdC are embedded in between twoadjacent aluminum layers

2) Heat Stability of PVdC during Lamination

Water Vapour Transmission Rate @ 38°C/90% RH

PE

PET

Al met

Adhesive

PET

Al metPVdC

Adhesive

PE

PET

PET

Al metPVdC

AdhesivePVdCAl met

Adhesive

PE

PET

PET

Al met

PVdCAdhesiveAl met

Adhesive

>> >


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0.015 0.016

0.021

0.029 0.028

0.008 0.010 0.007 0.009

0.00

0.01

0.01

0.02

0.02

0.03

0.03

0.04

WV

TR

[g

m-2

d-1

] 38

°C /

90

% R

H

PE

PET

PET


Adhesive

PE

PET

Al met

Adhesive

PET

Al metPVdC

Adhesive

State‐of‐the‐Art

Summary - Barrier Performance

PE

PET

Al met

Adhesive

PET

Al met

Adhesive

PET

Al metAdhesive

Effect of PVdC Lacquer Application in Laminates

Back-to-Face


Adhesion PerformanceMeasurement of Adhesion via Common Peel Tests

Al-plate(1 mm thick)

Double-sidedadhesive tape

Substrate film (e.g. PET)

Al layer

Peel arm: Heat sealablepolymer (e.g. EAA)

Metal adhesion:

EAA peel test

Force: F Laminate bondstrength:

DIN 55543-5:2017-10,

VIP sealed seamStrength: 90° peel test

DIN 55529:2012-09

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Adhesion AspectsMetal (Al) Adhesion Strength

1

1) No Delamination of Aluminium, Peel Test dominated by elongationof EAA peel-arm

2) Partial Delamination of Aluminium,Peel Test dominated by elongationof EAA peel-arm

High Metal Adhesion!

Specimen after Peel-Test

ElongatedPeel‐Arm

2 - 3 N/15 mm

> 3,5 N/15 mm

PET

Al met

2


Adhesion AspectsLaminate Bond Strength

F2F (Reference) B2F (1 x PVdC) F2F (2 x PVdC)

Laminate Structure,

Failure LocationFailure Mode

Bond strength[N/15 mm](PVdC / Al)

-1.0 ± 0.3

Adhesion Failure0.4 ± 0.3

Adhesion Failure

Bond strength[N/15 mm] Adhesive

3.8 ± 0.3Cohesion Failure



PE

PET

PET


Adhesive

PE

PET

Al met

Adhesive

PETAl metPVdC

Adhesive

PE

PET

PETAl metPVdC

AdhesivePVdCAl met

Adhesive

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Adhesion AspectsVIP Sealed-Seam Strength

PET / Al met. / Adh. / PET / Al met. / PVdC / Adh. / PE PE / Adh. / PVdC / Al met. / PET / Adh. / Al met. / PET

Sequence of heat‐sealed laminates at the seam

Force required to tear apart heat-sealed PE layers

30 N/15 mm


Conclusions and Outlook

PVdC lacquer enhances the barrier performance of the metallized films by up to a factor of 7: Application at industrial scale possible using non-toxic “green” solvents

Layer sequence in a laminate plays a very important role both for barrier and adhesion strength: The lacquer needs to be directly applied on the metallized layer It should not be embedded between the two metallized layers

Enhancement of water vapour barrier performance of laminates: A factor of 3 - 4 improvement in comparison to that of the same bi-laminate

without any PVdC layer

A factor of 2 - 3 better water vapour barrier performance than conventional tri-laminate structures with the same adhesion strength between the layers!

Cost reduction and water vapour barrier enhancement possibility in high barrier laminates for other various applications…

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„The project has received funding fromthe European Union‘s Horizon 2020 research and innovation programmeunder grant agreement No 723441“https://innovip-h2020.eu/

“Thank You” for understanding the Importance of Layer Sequence in VIP Laminates

Dr. Esra [email protected]+49 8161 491 507 Material development

Fraunhofer Institute for Process Engineering and Packaging (Fraunhofer IVV) Freising, Germany

Documents

Barrier Enhancement of Flexible Laminates, Adhesion ......May 22, 2017 · PVdC PE PET PET Al met Adhesive Al met Adhesive PE PET Al met PVdC Adhesive PVdC Al met Adhesive PE PET