Due to the unique nature of the digital inkjet printing process, UV-curable inkjet inks must meet precise and stringent requirements regarding a range of physicochemical properties.
Viscosity is a critical factor; it must be extremely low-typically in the range of 10–30 centipoise (cP) or even lower-to ensure the ink can pass smoothly through the micro-nozzles of the printhead and form stable droplets.
UV-curable inkjet inks require near-instantaneous curing (on the order of milliseconds) to prevent droplets from spreading or bleeding on the substrate, to enable "wet-on-wet" printing, and to avoid smudging or offsetting.
Surface tension must be precisely controlled to strike a balance between stable droplet formation and flight trajectory, and effective wetting of the substrate.
Pigment dispersion is a key physical property that influences the ink's chromaticity, opacity, viscosity, and overall system stability.
The ink must maintain thermal stability at the operating temperatures of the printhead (typically 40°C–50°C).
Furthermore, UV-curable inkjet inks must possess a specific level of electrical conductivity to meet the requirements of the equipment's electronic control systems. Color density determines the color saturation of the printed image, while additional requirements exist regarding environmental safety, weather resistance, and abrasion resistance.
Collectively, these physicochemical properties form the foundation that enables UV inkjet technology to achieve high-quality and highly efficient printing.
