Modeling Hydrophobic Decay and Additive Migration Dynamics in Treated Polyolefin Extrusions
Polyolefin surface treatment decays via polar group reorientation and slip agent bloom, requiring controlled additive specifications and inline bump corona.
Cold Foil Adhesion
Bonding Strength
Mechanical and chemical bonds formed between a decorative metallic layer and a printed adhesive determine the durability of embellishments on paper or plastic substrates. Successful cold foil adhesion depends on the compatibility of the uv curable adhesive with both the foil carrier and the underlying print surface. Precision is required.
This property ensures that the metallic flakes transfer cleanly from the polyester carrier film to the targeted areas of the design. Proper transfer avoids waste.
Application Variable
Surface energy and curing speed dictate the quality of the transfer during the converting stage. When the adhesive remains too wet or dries too quickly before contact with the foil, cold foil adhesion weakens and causes the metallic layer to lift or flake away. Operators adjust the lamp intensity and press speed to find the window where the bond remains stable.
The presence of surface contaminants or low surface tension on the substrate often disrupts the interface and leads to poor results. Furthermore, the smoothness of the base board affects the contact area available for the adhesive, with rough surfaces requiring higher coat weights to achieve a uniform bond.
Testing Method
Evaluation of the finished embellishment typically involves standardized tape tests to measure the resistance of the foil to peeling. A strip of pressure sensitive tape is applied to the foiled area and removed at a consistent angle to check for any loss of material. If the cold foil adhesion is insufficient, the metallic layer stays on the tape and leaves the substrate exposed.
This failure indicates a need for better surface treatment or a change in adhesive chemistry.