PU-Acrylate UV Resins

PU-acrylate (urethane acrylate) gives flexibility, elongation and adhesion, and is the choice when the coated part has to bend or when adhesion is the hard requirement. Epoxy acrylate gives hardness, gloss and chemical resistance at lower cost, and is the choice for rigid substrates. Many formulations blend both to reach a specific balance.

Functionality is the number of reactive acrylate groups per molecule. Low functionality (around 2) cures more slowly and gives a softer, more flexible, more adhesive film. High functionality (6 and above) cures faster and gives a harder, more crosslinked, more chemically resistant film with less elongation. It is the main dial in a UV formulation.

LED UV cure depends primarily on the photoinitiator package being matched to the LED output wavelength, rather than on the oligomer. PU-acrylate oligomers can be formulated for LED cure — we can advise on the photoinitiator selection as part of application support.

Aliphatic urethane acrylates resist yellowing and are the choice where colour stability under light exposure matters, including clear coats and white systems. Aromatic urethane acrylates cost less and cure well but yellow over time, which is acceptable in pigmented or non-critical applications.

Yes, and PU-acrylate is usually the right family for it precisely because of the flexibility requirement. The considerations are substrate heat sensitivity, adhesion to the treated film and — for food packaging — migration, which has to be evaluated against the specific regulation and end use.

Oxygen quenches the radical cure at the film surface, leaving it tacky while the bulk is cured. It is addressed by inerting with nitrogen, by increasing photoinitiator or lamp intensity, or by formulating with amine synergists — which is one reason amino acrylates exist as a product family.