Adhesion to Foil More than Just a One-Sided Story Gnter Schubert - - PowerPoint PPT Presentation

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Adhesion to Foil More than Just a One-Sided Story Gnter Schubert - - PowerPoint PPT Presentation

Oct 21, 2023 216 likes •544 views

Place for, company logo from speaker Adhesion to Foil More than Just a One-Sided Story Gnter Schubert Otto Plassmann Session: Barrier Packaging - Paper 7698 Structure Introduction to aluminium foil surfaces Storage of

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Place for, company logo from speaker

Adhesion to Foil – More than Just a One-Sided Story

Günter Schubert Otto Plassmann Session: Barrier Packaging - Paper 7698

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Adhesion to Foil – More than Just a One-Sided Story 2

Structure

PE

  • Introduction to aluminium foil surfaces
  • Storage of semi-finished laminates
  • Surface change during storage
  • Case studies in adhesion failure
  • Examination of foil/film interfaces using IR-ATR
  • Carbonyl Index –not only an issue of PE oxidation
  • Conclusions
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Adhesion to Foil – More than Just a One-Sided Story 3

Delaminations Occurring in Extrusion Coatings

Aluminium foil LDPE Printed paper Delamination

Pouch for a typical German barbecue spice mixture

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Adhesion to Foil – More than Just a One-Sided Story 4

Structure of a Flat Pouch

Internal contact with packaged good

PE

Flat pouch PEcoex 30 µm Alufoil 9 µm PEex 20 µm Paper 60 g/m² (printed)

Pouch for a typical German barbecue spice mixture

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Adhesion to Foil – More than Just a One-Sided Story 5

Coil Annealing

Oxygen can enter the coil Rolling oil can exit via the coil ends Core

Roling oil concentration

tbegin t1 t2 t3 tend

Furnace Inside the coil Furnace

Adhesion to Foil – More than Just a One-Sided Story

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Adhesion to Foil – More than Just a One-Sided Story 6

Oxide Growth During Coil Annealing

Metal/oxide interface where oxide growth takes place Top layer Barrier layer Aluminium Barrier layer Aluminium 1-8 nm 1-6 nm 1-2 nm 2-8 nm Thin film of rolling oil Rolling oil residues Oxide Top layer

Before annealing After annealing If annealing time is too long, the oxide layers of adjacent surfaces can stick together - resulting in poor decoiling and the risk of web breaks

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Adhesion to Foil – More than Just a One-Sided Story 7

Coiling Pressure Distribution in a Coil (Schematic)

Core Relative pressure Low High

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Adhesion to Foil – More than Just a One-Sided Story 8

Wettability Profile Across a Foil Web

Wettability High Moderate High (water) Relative Moderate High Moderate winding pressure

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Adhesion to Foil – More than Just a One-Sided Story 9

Different Types of Chemical Bonding to Aluminium Foil

Top layer Barrier layer Metal Oxide O O O C = O OH O Si - O - H O O (CH2)6 HO - C Hydrogen bond Soap Graft silane O C = O CH 2 CH 2 Al - O - Al - O - Al Al - O - Al - O

  • Al - O - Al - O - Al

O O OH Al - O - Al - O - Al

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Adhesion to Foil – More than Just a One-Sided Story 10

Contact between the blank side and the adjacent coated side can lead to a transfer of matter and adversely affect adhesion in the subsequent converting step (e.g. a 50 g/m²-paper with 4 – 8% humidity contains 2 - 4 g/m² water)

Practice of Storage of Single-Side Converted Aluminium Foil

Side A coated Side B blank

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Adhesion to Foil – More than Just a One-Sided Story 11

Aluminium oxide layer Aluminium foil H O

Hydroxylation of an Oxide Layer on Aluminium Foil Exposed to Air

Oxide layer H H O H H O H H O H H O H H O H OH C O R OH C O R OH C O R OH C O R

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Adhesion to Foil – More than Just a One-Sided Story 12

*Al-Verbund, 16 825 311 Al-Seite, Polymer abgezogen, good, MW3, GG *Al-Verbund, 16 825 312 Al-Seite, Polymer abgezogen, bad, MW3, GG 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 0,18 0,20 0,22 0,24 0,26 0,28 0,30 0,32 0,34 0,36 0,38 0,40 Ext inkt ion 500 1000 1500 2000 2000 3000 4000 Wellenzahlen (cm-1)

Absorbance ν(A-O) ∼ 950 cm-1 ν(O-H) ∼ 3300 cm-1 Wave number [cm-1]

*Al-Verbund, 16 825 311 Al-Seite, Polymer abgezogen, good, MW3, GG *Al-Verbund, 16 825 312 Al-Seite, Polymer abgezogen, bad, MW3, GG 0,32 0,34 0,36 0,38 0,40

0.30 0.20 0.10 0.00

Hydroxylation and Oxide Growth on an Al/PE Laminate Stored at Elevated Temperature with High Humidity

4000 3000 2000 1500 1000 500

  • -- IR-ATR of aluminium surface of newly produced laminate
  • -- IR-ATR of aluminium surface after storage
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Adhesion to Foil – More than Just a One-Sided Story 13

Changes Occurring in Oxide Layer on Aluminium Foil Exposed to Air

Aluminium oxide layer H O Oxide layer H H O H H O H H O H OH C O R OH C O R OH C O R C O O R C O O R H O H H O H Hydroxylated top layer H O H Aluminium foil

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Adhesion to Foil – More than Just a One-Sided Story 14

Aluminium oxide layer Aluminium foil H O

Bonding to an Oxide Layer on Aluminium Foil Exposed to Air

Oxide layer H H O H H O H OH C O R C O O R C O O R H O H C O O CH CH2 CH2 CH2 CH2 CH2 CH2 CH2 H O H C OH O R Hydroxylated top layer Polymer chain of coating

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Adhesion to Foil – More than Just a One-Sided Story 15

Coiling and Storage of Aluminium Foil Converted on One Side - Transfer of Matter from the Adjacent Surface

Clay-coated paper Extruded PE Aluminium foil

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Adhesion to Foil – More than Just a One-Sided Story 16

*Al-Verbund, Schlechtmuster "Bad, 2.5 Monate", Rand, MW3, GG *Al-Verbund, Gutmuster "48h", Rand, MW3, GG 0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 0,18 0,20 Ext inkt ion 500 1000 1500 2000 2000 3000 4000 Wellenzahlen (cm-1)

Transfer of Ester Wax Species in a Coil from a Coated Paper to an Aluminium Surface

Absorbance 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 4000 3000 2000 1500 1000 500 Wave number [cm-1] ν(Al-O) 950 cm-1 Newly produced laminate, aged for 3d/40°C in a stack Surface plaque after a storage time of 10 weeks

Processing aid on foil surface leads to poor ink adhesion

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Adhesion to Foil – More than Just a One-Sided Story 17

Coiling and Storage of Aluminium Foil Converted on One Side – an Adhesion Issue

Extrusion coating Aluminium foil Printing pattern

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Adhesion to Foil – More than Just a One-Sided Story 18

O

Printing-Pattern-Related Adhesion of an Extrusion Coating on Aluminium Foil

Areas of poor adhesion Areas of good adhesion

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Adhesion to Foil – More than Just a One-Sided Story 19

O

Different Peel Patterns of the PE Coating

Area with the best adhesion Stick-slip pattern ⊥ Peel direction Area with the poorest adhesion No peel pattern

MD + peel direction

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Adhesion to Foil – More than Just a One-Sided Story 20

Examination of Peel Interfaces between Coating and Foil Using IR-ATR

Pressure stamp Delaminated interface (on coating or foil) Diamond crystal IR spectrometer ZnSe crystal

Adhesion to Foil – More than Just a One-Sided Story

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Adhesion to Foil – More than Just a One-Sided Story 21

O

IR-ATR Spectra of Outer Coating Surface and Peel Interfaces

*Polymer, Zone good, glänzende Seite, MW3, ATR *Polymer, Zone good, matte Seite, MW3, ATR *Polymer, Zone bad, glänzende Seite, MW3, ATR *Polymer, Zone bad, matte Seite, MW3, ATR 0,000 0,002 0,004 0,006 0,008 0,010 0,012 0,014 0,016 0,018 0,020 0,022 0,024 0,026 0,028 0,030 0,032 0,034 Ext inkt ion 1650 1700 1750 1800 Wellenzahlen (cm-1)

1800 1750 1700 1650 Wave number [cm-1] 0.30 0.20 0.10 0.00 Absorbance Ester species present in cases of poor adhesion ( ν(C=O) 1739 cm-1) Acid compounds ν(C=O) 1719 cm-1

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Adhesion to Foil – More than Just a One-Sided Story 22

Preparation of Interfaces in Aluminium/ Polyethylene Laminates for IR-ATR

Aluminium foil dissolved in dilute acid

Cardboard or paper LDPE-lamination layer Aluminium foil Side A Side B Coating (single or coex) Information depth of IR-ATR ~ 2 - 4 µm

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Adhesion to Foil – More than Just a One-Sided Story 23

Frontier of acid attack

Polyethylene Surface at the Frontier of Acid Attack on Aluminium

Aluminium, not yet dissolved PE-coating surface for examination

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Adhesion to Foil – More than Just a One-Sided Story 24

Oxidation Index Dependent on the Surface Preparation Method

*Al-Verbund, LD MFR4, Poly/Al-Seite, HCl, 2cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, HCl, 19cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, HCl, 37.5cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, HCl, 56cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, HCl, 73cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, Polymer abgezogen, 2cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, Polymer abgezogen, 19cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, Polymer abgezogen, 37.5cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, Polymer abgezogen, 56cm, GG *Al-Verbund, LD MFR4, Poly/Al-Seite, Polymer abgezogen, 73cm, GG
  • 0,000
0,005 0,010 0,015 0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065 Ext inkt ion 1550 1600 1650 1700 1750 1800 Wellenzahlen (cm-1)

0.60 0.50 0.40 0.30 0.20 0.00 1800 1750 1700 1650 1600 1550 Wave number [cm-1] Absorbance (scale) ν(C=O) 1719 cm-1 Al foil dissolved in acid PE peeled off - lower intensity!

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Adhesion to Foil – More than Just a One-Sided Story 25

Preparation of Interfaces in Aluminium/ Polyethylene Laminates by Peeling

Aluminium foil Extrusion coating Functional groups close to the surface Aluminium foil Extrusion coating Oxide layer + coating residues Peel direction ∼ 180° Better adhesion leads to elongation of the coating and lower concentration of C=O-groups close to the surface Functional groups close to the surface

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Adhesion to Foil – More than Just a One-Sided Story 26

Does the Oxidation Index Correlate with Adhesion Performance?

*Al-Verbund, Probe 1, OK-gelb, links, Polymerseite, MW3, GG *Al-Verbund, Probe 1, OK-gelb, mitte, Polymerseite, MW3, GG *Al-Verbund, Probe 1, OK-gelb, rechts, Polymerseite, MW3, GG *Al-Verbund, Probe 2, OK-gelb, rechts, Polymerseite, MW3, GG *Al-Verbund, Probe 2, OK-gelb, mitte, Polymerseite, MW3, GG *Al-Verbund, Probe 2, OK-gelb, links, Polymerseite, MW3, GG *Al-Verbund, Probe 3, OK-rot, rechts, Polymerseite, MW3, GG *Al-Verbund, Probe 3, OK-rot, mitte, Polymerseite, MW3, GG *Al-Verbund, Probe 3, OK-rot, rechts, Polymerseite, MW3, GG *Al-Verbund, Probe 4, BAD-rot, links, Polymerseite, MW3, GG *Al-Verbund, Probe 4, BAD-rot, mitte, Polymerseite, MW3, GG *Al-Verbund, Probe 4, BAD-rot, rechts, Polymerseite, MW3, GG 0,015 0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 Ext inkt ion 1620 1640 1660 1680 1700 1720 1740 1760 1780 1800 Wellenzahlen (cm-1)

Absorbance (scale) 0.60 0.50 0.40 0.30 0.20 1800 1760 1720 1680 1640 Wave number [cm-1] ν(C=O) 1718 cm-1 Adhesion Al/PE Poor Good Good

IR-ATR of PE-coatings

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Adhesion to Foil – More than Just a One-Sided Story 27

Melt Creep Behaviour of Extrusion Coatings (LDPE MI 4)

Measurement set-up Cone-plate geometry 190 °C 300 s / 100 Pa 600 s / 0 Pa Observation of creep deformation and elastic back deformation Molten extrusion-coated film

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Adhesion to Foil – More than Just a One-Sided Story 28

Melt Creep Behaviour of Differently Oxidised Extrusion Coatings (LDPE MI 4)

Deformation γ [1] 5 10 15 20 Time [min] Shear stress [Pa]

Materials

  • Granules MI 4
  • Good (coating)
  • Bad (coating)
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SLIDE 29 *Al-Verbund, India, Al-Seite, MW3, Diamant *Al-Verbund, India, Al-Seite, MW3, EtOH, Diamant Ölsäure, Firma: Merck, 2001, Diamant 0,02 0,04 0,06 0,08 0,10 0,12 0,14 0,16 0,18 0,20 Extinktion 1000 2000 2000 3000 4000 Wellenzahlen (cm-1)

1710 cm-1 ν(C=O) oleic acid

Delamination of a Flat Pouch

Al-surface 1710 cm-1 ν(C=O) before and after washing

Oleic acid ν(C=O) 1710 cm-1 ν(C-H) Absorbance 4000 3000 2000 1000 Wave number [cm-1] ν(Al-O) 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02

Adhesion to Foil – More than Just a One-Sided Story 29

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Adhesion to Foil – More than Just a One-Sided Story 30

Conclusions

  • Aluminium foil surface ensures good wetting and

robust adhesion, safely stored in a coil

  • Exposed aluminium surfaces in semi-finished

laminates can undergo changes when in contact with adjacent surfaces of other coiled materials

  • Matter transfer during storage can be

assessed/predicted by means of laboratory tests

  • IR-ATR is a valuable tool for identifying superficial

plaques or adhesion-related interfacial changes

  • Packaged goods can have adverse and

unpredictable effects on adhesion

  • Adhesion chemistry of polyethylenes is more than

the Carbonyl Index

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Adhesion to Foil – More than Just a One-Sided Story 31

NOTICE NOTICE

COMPLAINT DEPARTMENT COMPLAINT DEPARTMENT 200 MILES 200 MILES

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Thank you for lending me your ear

Contacts: Guenter.schubert@hydro.com Otto.plassmann@innovene.com