UV resin is the main component of the UV curing system. It is an oligomer that can undergo physical and chemical changes in a short period of time after being exposed to UV light, and rapidly crosslink and cure. After curing of UV coating, the basic performance of the coating film largely depends on its main film-forming material – UV resin, and the performance of UV resin is determined by the macromolecular polymer that constitutes this resin. The molecular structure, molecular weight, double bond density and glass transition temperature of the polymer will affect the performance of the resin. The traditional oily UV resin has large molecular weight and viscosity, so it has shortcomings in coating process and film performance control. Acrylate active diluent [1] contains unsaturated double bonds and has low viscosity. Adding it to the UV curing system can reduce the resin viscosity, improve the cross-linking density of the resin, and improve the film performance of the resin, so it is widely used. However, most active diluents are toxic and irritating to human skin, mucous membrane and eyes. In addition, the diluent is difficult to react completely during UV irradiation, and the residual monomer will directly affect the long-term performance of the curing film, which limits its application in packaging materials of food hygiene products.
Waterborne UV resin refers to the UV resin that is soluble in water or can be dispersed with water. Its molecules contain a certain amount of hydrophilic groups such as carboxyl, hydroxyl, amino, ether or amide groups, as well as unsaturated groups such as acryloyl, methacryloyl or allyl groups. At present, waterborne UV resins mainly include waterborne polyacrylate, waterborne polyester acrylate, waterborne epoxy acrylate and waterborne polyurethane acrylate.
As a new type of polymer, hyperbranched polymer has a spherical structure, a large number of active end groups, and no entanglement between molecular chains. Hyperbranched polymers have the advantages of easy dissolution, low melting point, low viscosity and high reactivity. Therefore, acryloyl groups and hydrophilic groups can be introduced to synthesize waterborne UV curable oligomers, which opens a new way for the preparation of waterborne UV resins.
Post time: Oct-11-2022