Ink Resin System Impact: Resin, a crucial component of ink, serves as a carrier for pigments, connecting powder-like pigments and fillers. It enables the ink to dry and form a film on the printing substrate. The resin system is a key factor affecting adhesion on the substrate, and its compatibility with different substrates, such as BOPP, PET, and NY, is essential for achieving optimal adhesion. Different substrates require specific ink resin types to ensure good adhesion.
Impact of Pigment Dispersion: Pigments, as carriers of vibrant colors in ink, need to be finely crushed into uniform particles and evenly distributed in the resin. The quality of pigment dispersion significantly affects the ink's fineness, glossiness, viscosity, stability, coloring power, coverage, and adhesion. A well-dispersed system enhances adhesion by creating a uniform and dense resin interface with pigment particles on the plastic substrate surface.
Solvent Influence: In solvent-based inks commonly used in plastic gravure printing, organic solvents play a crucial role and greatly influence adhesion on plastic substrates. The thorough evaporation of solvents after printing is crucial for adhesion. The solvent composition, including the ratio of true solvents to diluents, affects the ink's drying capability and overall adhesion.
Impact of Film Surface Treatment: Plastic packaging printing often involves materials like BOPP, PET, and NY, which, despite their smooth surfaces, require corona treatment to enhance ink adhesion. After corona treatment, the film surface develops active groups, making it more receptive to most inks and solvents. Confirming the surface treatment status before printing is essential, with target surface tension levels for BOPP and PET being 38mN/m and 52mN/m, respectively.
Effect of Film Moisture Absorption: Certain films, like NY, are prone to moisture absorption, significantly affecting printing performance and adhesion. Moisture absorption leads to decreased ink adhesion, making it crucial to store and print these films in dry conditions. Moisture prevention measures, such as wrapping unused film in high barrier materials like aluminum foil, are necessary. Moisture-absorbed films should undergo drying in a maturation chamber before evaluating their usability.
Influence of Shallow Screen Printing: Shallow screen printing, often employed in intricate color patterns for packaging design, may pose challenges. The lower ink volume in shallow screen printing, coupled with potential dry plate issues, can result in inadequate ink transfer to the film. This, along with insufficient solvent wetting, leads to a compromised ink-film interface, affecting adhesion. To address this, adding slow-drying solvents, increasing printing speed and drying temperature