Monomers in UV inks and coatings reduce viscosity and become part of the cured film. Their functionality, the number of acrylate groups per molecule, drives the result.
Functionality
- Mono-functional: low viscosity, flexibility, adhesion and low shrinkage, but slower cure
- Di-functional (such as DPGDA, TPGDA, HDDA): the workhorses, balancing viscosity and cure
- Tri- and higher (such as TMPTA, PETA, DPHA): fast cure, hardness and chemical resistance, but more shrinkage and brittleness
Backbone
Ethoxylated and propoxylated versions lower skin irritation potential and increase flexibility; cyclic and aromatic structures improve adhesion and hardness.
Safety and regulations
Acrylate monomers are skin sensitisers, and some are restricted for particular uses. Always check the current classification and the end use, especially for food packaging.
