1 Coating Plasma Innovation Atmospheric Plasma treatment effect

1 Coating Plasma Innovation Atmospheric Plasma treatment, effect on the plasma chemistry on adhesion Nicolas Vandencasteele

2 Plasma Applications Adhesion improvement Conclusion

3 Plasma 4 th state of matter: ionized gas

4 Cold atmospheric plasma Cold: Tgas < 100 °C Tions, neutrals < 100 °C Telectrons ≈ 10 000 °C Hot: Tgas ≈ Tions, neutrals ≈ Telectrons 104<T<108 °C Atmospheric: Plasma gas is at atmospheric pressure Open reactor, high density of particles Energetic electrons chemistry

5 Corona High Voltage Ambient air Filamentary discharge • Used for activation or cleaning • Flat substrate • Most of the time need to be used inline with other process • Gas used: none (ambient air)

6 Plasma DBD High Voltage Controlled atmosphere Homogeneous discharge • Used for activation or cleaning and deposition • Flat substrate • Used online or offline • Gas used: N 2, (Ar, He)

7 Plasma vs Corona Surface energy measurements on BOPP film Controlled chemistry Stable treatment

8 Plasma vs Corona Microscopy (AFM) image of BOPP film 1 µm x 1 µm images (Tapping) Untreated Es ≤ 30 m. N/m Plasma DBD Es = 60 m. N/m Corona Es = 38 m. N/m Identical discharge power Controlled chemistry, homogenous discharge no surface damage

9 Process Plasma gas + dopant Dopant: ppm of reactive gases mixed with plasma gas (only safe gas green top bottles)

10 APPLICATIONS

11 Applications: Cleaning Plasma CO 2↗, H 2 O ↗ … Contaminated surface Surface contamination Cleaned sample Removal of surface contamination without substrate degradation

12 Applications: Grafting Amide Amine Gas: N 2 + dopants H O C N C O NH 2 O H H H Imide C C C O C N O C H O C Surface functionalization C C O C

13 Applications: Grafting 4. 5 4 Standard 3. 5 Atomic % (XPS) Quantity (a. u. ) Advanced Dopant 1 1 3 Advanced Dopant 2 2 2. 5 2 1. 5 1 0. 5 0 Amine Amide Imide Grafting of nitrogen containing groups Tunable surface functionalization

14 Applications: Coating Specific molecules (precursor ) are added to the plasma gas. Those molecules are activated ( ) by the plasma and react with the sample surface to form a thin film. Si. Ox film (hydrophilic) HMDSO precursor Si. Cy. Ox film (hydrophobic) Coating nature dependend on precursor AND plasma chemistry

15 ADHESION IMPROVEMENT

16 ECTFE – Surface energy increase Very limited ageing after 3 weeks

17 ECTFE – Adhesion increase ECTFE laminate (Araldite 2028) 70 60 200 50 150 40 100 30 20 50 10 0 Surface energy [m. N/m] Peel Force [N/m] 250 0 Untreated Corona Plasma 1 Peel Force Plasma 2 Plasma 3 Surface Energy Different plasma chemistries Surface energy is not the main factor improving adhesion

18 ECTFE – Adhesion increase ECTFE laminate (Araldite 2028) 12 10 200 8 150 6 100 4 50 2 0 0 Untreated Corona Plasma 1 Peel Force Plasma 2 Plasma 3 %N grafted Chemistry, not SE, is the main factor improving adhesion at. % N Peel Force [N/m] 250

19 PET – Adhesion increase PET thermoset adhesive 900 50 Peel Force [N/m] 800 700 40 600 30 500 400 20 300 200 10 100 0 0 Untreated Corona Plasma a Peel force Plasma b Plasma c Surface Energy Adhesion not always directly related to surface energy Surface Enrgy [m. N/m] 60 1000

20 PET – Adhesion increase PET thermoset adhesive 4 1000 3. 5 800 3 700 600 2. 5 500 2 400 1. 5 300 1 200 0. 5 100 0 0 Untreated Corona Peel force Plasma a Plasma b Plasma c Surface Composition Chemistry, not SE, is the main factor improving adhesion At. % Nitrogen Peel Force [N/m] 900

21 Adhesion increase Acrylic PET Untreated vs Corona 15% Untreated vs Plasma Up to 85% Corona vs Plasma 35% Thermoset PET Untreated vs Corona Untreated vs Plasma Corona vs Plasma 200% Up to 2300% 800% Araldite 2028 ECTFE Untreated vs Corona Untreated vs Plasma Corona vs Plasma 1000% Up to 4870% 350% Results depend on adhesive and plasma chemistries

22 Conclusion • Plasma treatment enables stable modification of surface energy • Plasma allows to tailor the surface modifications to specific adhesive and substrate combination • Level of adhesion can be controlled over a large range • Plasma treatment can be applied to almost any materials (PEEK, Fluorinated polymers, PI, metals, paper…)