Polyethylene Film Slip Additive Migration and Surface Accumulation Principles
Polyethylene slip amides migrate via matrix supersaturation, dropping film kinetic friction below 0.22 through surface crystallization within 72 hours.
Corona Discharge Treatment
Meaning
Atmospheric plasma oxidation alters non-polar polymer film surfaces by breaking molecular chains to generate functional groups that improve ink or adhesive receptivity. Corona discharge treatment utilizes a high voltage electrical field to ionize air between a conductive roll and a dielectric electrode. This ionization creates an avalanche of electrons that impact the plastic substrate at a microscopic level.
The process increases surface energy to promote uniform wetting during printing or coating operations.
Surface Activation
Polymer film producers apply this method to materials like polyethylene and polypropylene which naturally resist chemical bonding due to their low surface tension. Corona discharge treatment modifies only the top molecular layers without changing the bulk properties of the plastic sheet. Processing speed and power density determine the intensity of the surface oxidation.
Variations in atmospheric humidity affect the discharge uniformity and the resulting chemical composition of the treated surface.
Moulding Integration
Plastic processors occasionally treat moulded parts before painting or bonding to ensure structural integrity of the applied finishes. Corona discharge treatment resolves issues where virgin resin formulations lack the necessary polar sites for permanent adhesion. Drift in the treatment intensity leads to inconsistent coating layers or premature bond failure during field use.
Correct levels of surface energy prevent delamination when multiple materials bond in a single assembly.
Standard Specification
Quality control teams define target surface tension values in dynes per centimeter based on the specific requirements of the chosen ink or adhesive system. Corona discharge treatment leaves a measurable signature on the film that decreases over time as polymer chains reorient away from the surface. Datasheet values represent the minimum energy levels expected immediately following production on the line.
Operators manage the aging effect by monitoring the decline in surface energy from the point of manufacture to the moment of final application.