Phosphorus-Containing Telomers as UV-Curable Binders for Solvent-Free Varnish Coatings

Purpose：The work develops phosphorus-containing telomers as binders for solvent-free UV varnishes and examines how different phosphorus telogens affect cure, hardness, abrasion, water resistance and glass adhesion.

System and methods：Butyl acrylate, methyl methacrylate, hydroxyethyl acrylate and styrene were UV-telomerized with dimethyl phosphite, dibutyl phosphite, diphenyl phosphite or dibutyl phosphate. Photo-DSC and FTIR followed the reaction, and the telomers were formulated with PETIA and a photoinitiator.

Key findings and mechanism：Phosphorus-containing telomers were synthesized with four phosphorus telogens under UV initiation and monitored by photo-DSC and FTIR. The varnishes combined P-telomers, PETIA and a HAP photoinitiator. Dimethyl phosphite telomers gave higher hardness and better scratch, water and solvent resistance; diphenyl phosphite telomers gave the strongest glass adhesion; gloss was not significantly reduced. Different phosphorus groups alter polarity, chain flexibility, surface enrichment and interaction with glass hydroxyls. Softer or more mobile phosphorus structures can improve interfacial adhesion, while crosslink density and hard-segment content mainly control hardness and abrasion.

Application value and limits：Different phosphorus groups create different balances of hardness, adhesion and chemical resistance, allowing selection by substrate and performance target. The study concerns clear, solvent-free UV varnishes without pigments. Pigmented or thick-film systems must additionally consider UV absorption, photoinitiator competition, storage stability and the effect of phosphorus groups on cure speed.