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Nicolas Vandencasteele
Coating Plasma Innovation Atmospheric Plasma treatment, effect on the plasma chemistry on adhesion Nicolas Vandencasteele
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Plasma Applications Adhesion improvement Conclusion
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Plasma 4th state of matter: ionized gas
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Cold atmospheric plasma
Tgas < 100 °C Tions,neutrals < 100 °C Telectrons ≈ °C Atmospheric: Plasma gas is at atmospheric pressure Open reactor, high density of particles Hot: Tgas ≈ Tions,neutrals ≈ Telectrons 104<T<108 °C Energetic electrons chemistry
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Corona Used for activation or cleaning Flat substrate
Most of the time need to be used inline with other process Gas used: none (ambient air) High Voltage Ambient air Filamentary discharge
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Plasma DBD Used for activation or cleaning and deposition
Flat substrate Used online or offline Gas used:N2, (Ar, He) High Voltage Controlled atmosphere Homogeneous discharge
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Controlled chemistry Stable treatment
Plasma vs Corona Surface energy measurements on BOPP film Controlled chemistry Stable treatment
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Controlled chemistry, homogenous discharge no surface damage
Plasma vs Corona Microscopy (AFM) image of BOPP film 1 µm x 1 µm images (Tapping) Es = 38 mN/m Es ≤ 30 mN/m Es = 60 mN/m Untreated Plasma DBD Corona Identical discharge power Controlled chemistry, homogenous discharge no surface damage
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Process Plasma gas + dopant Dopant:
The plasma is generated between the electrodes (red part) and the back roll (grey part). The substrates runs directly through this zone where the plasma is created, then where the plasma is most reactive, then where the plasma is most efficient. Dopant: ppm of reactive gases mixed with plasma gas (only safe gas green top bottles)
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APPLICATIONS The plasma is generated between the electrodes (red part) and the back roll (grey part). The substrates runs directly through this zone where the plasma is created, then where the plasma is most reactive, then where the plasma is most efficient.
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Applications: Cleaning
Cleaned sample CO2↗, H2O ↗ … Contaminated surface Plasma Surface contamination Removal of surface contamination without substrate degradation
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Applications: Grafting Surface functionalization
H Amine Amide Imide N 2 NH Gas: N2 + dopants Surface functionalization
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Applications: Grafting Tunable surface functionalization
Dopant 1 Dopant 2 Tunable surface functionalization
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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. SiOx film (hydrophilic) HMDSO precursor SiCyOx film (hydrophobic) Coating nature dependend on precursor AND plasma chemistry
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ADHESION IMPROVEMENT The plasma is generated between the electrodes (red part) and the back roll (grey part). The substrates runs directly through this zone where the plasma is created, then where the plasma is most reactive, then where the plasma is most efficient.
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ECTFE – Surface energy increase
Very limited ageing after 3 weeks
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ECTFE – Adhesion increase
Different plasma chemistries Surface energy is not the main factor improving adhesion
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ECTFE – Adhesion increase
Chemistry, not SE, is the main factor improving adhesion
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PET – Adhesion increase
Adhesion not always directly related to surface energy
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PET – Adhesion increase
Chemistry, not SE, is the main factor improving adhesion
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Adhesion increase Results depend on adhesive and plasma chemistries
Acrylic PET Untreated vs Corona 15% Untreated vs Plasma Up to 85% Corona vs Plasma 35% Thermoset PET Untreated vs Corona 200% Untreated vs Plasma Up to 2300% Corona vs Plasma 800% Araldite 2028 ECTFE Untreated vs Corona 1000% Untreated vs Plasma Up to 4870% Corona vs Plasma 350% Results depend on adhesive and plasma chemistries
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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…)
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