How does UV curable resin work?

Ultraviolet (UV) curing is a method of irradiating UV rays into UV curing resin which causes it to cure much faster than Epoxy resin. Unlike Epoxy resin, this is a single component resin which cures within 2-4 minutes when placed under a UV lamp. Longer curing times are applicable when the resin is exposed to sunlight.

UV curable resin is composed of monomers, oligomers, photopolymerization initiators and additives.

When exposed to UV light, the photo initiator undergoes a chemical reaction that allows it to bond independent oligomers and monomers into a more complex chain called a polymer. The bonding process called a “photopolymerization reaction” is what takes a resin from its liquid state to a solid state.

Reference: https://www.ocirtech.com/what-is-uv-curing