Surface treatment plays a crucial role in achieving optimal adhesion and performance for various materials. Here are ten strategies to enhance your surface treatment results:
- Consistent Surface Tension Measurement:
When measuring surface tension, stick to a single dyne solution consistently. Different formulations can yield varying results due to their dispersive or polar characteristics. Corroborate dyne level readings with contact angle protocols using deionized water to improve accuracy.
- Understanding the "Wettability Gap":
Understanding what we know as the “Wettability Gap” can help to quickly diagnose issues with wet-out of inks, coatings and adhesives. This Gap is defined as the difference in surface energy (dynes/cm) between the base material and the solution being applied to the surface of that base material. Knowing the surface tensions of these solutions is a critical first step in determining what will be required of a surface treatment system.
- Controlling Power Density:
Properly control the watt density of corona treatment to avoid the formation of low molecular weight oxidized materials (LMWOM). Uncontrolled LMWOM generation can negatively impact ink adhesion.
- Regular Ground Roll Cleaning:
Prevent particle contamination on the ground roll of a corona treater to avoid backside ionization and inadequate surface energy on the top side. Cleaning the ground roll and preventing contamination will help prevent backside treatment issues.
- Optimal Wrap Angle and Web Tension:
Maintain a specified wrap angle and web tension to ensure proper treatment. A 180-degree web wrap angle around the ground roll is preferred to minimize the risk of backside treatment.
- Managing Additive Migration:
Be mindful of material additives' impact on surface treatment. For instance, fatty-acid based material modifiers may require uniform surface cleaning to prevent downstream delamination.
- Consider a Higher Dielectric Ground Roll Covering:
Evaluate using higher dielectric ground roll coverings like ceramic or glass, which enable the ground roll to accept more charge, leading to an increased number of surface reactive sites.
- Avoid Excessive Heat Exposure:
Avoid subjecting treated materials to high heat before conversion, as corona treatment can degrade under such conditions. Plasma treatments may offer better stability due to discharge density and chemical bonding.
- Introduce Atmospheric Plasma Technology:
Incorporate atmospheric plasma technology during conversion to introduce functional groups that increase surface tension and extend treatment longevity. This can be achieved by introducing oxygen to increase surface oxidation.
- Install Static Charge Equalizing Nip Rollers for Web Wrinkling:
To address web wrinkling, install static charge equalizing nip rollers within the station before the material passes through the corona. This helps to prevent backside treatment and minimize wrinkling caused by voltage drop.
By implementing these ten strategies, you can significantly enhance the effectiveness of your surface treatment processes, leading to improved adhesion and overall material performance.