Research On Preparation Of Hydrophilic UV-Curing Anti-fogging Coatings

Fogging and dewing condensation on the surface of transparent optical materials is a common problem. There are many methods to solve such problem, such as physical heating, painting an hydrophilic or hydrophobic film. The traditional methods to prepare film by thermo-curing bring the follow flaws:high energy consumption, low-efficiency, easy to make deformation of base materials. What's more, it is easy to contamination and difficult to clean. In this thesis, by means of combining the advantage of UV coatings (efficient, energy conservation, curable at room temperature, etc.) and the low surface tension of fluoro-containing surfactant, we prepared a new type of photo-curable coatings using an photo-sensitive hydrophilic acrylate as a basic resin, to overcome the defect of traditional anti-fogging thermo-curing coatings. Firstly, a series of oligomeric fluoro-containing urethane acrylates with surface activity were synthesized, using poly(ethylene oxide) fluoro-alkyl ether,2,4-toluene diisocyanate (TDI) or isopropyl ketone diisocyanate (IPDI),2-hydroxyethyl acrylate (HEA), pentaerythritol triacrylate (PETA) as raw materials. The results demonstrated that such oligomers can significantly reduce the surface tension of water. A series of well-defined hydrophilic acrylate resins were synthesized subsequently via the visible light activating room-temperature RAFT polymerization, light-triggered removal of chain transfer agent residues and ring-opening reaction of glycidyl methacrylate, using acrylic acid, 2-hydroxyethyl acrylate (HEA), poly(ethylene glycol) monomethyl ether acrylate as hydrophilic monomers, and ethyl acrylate as a hydrophobic monomer. The anti-fogging UV-curable paint was prepared using film-forming substance such as acrylic acid,2-hydroxyethyl acrylate, methyl acrylate, poly(ethylene glycol) acrylate, cross-linkers, photo-initiators and other additives, etc. The anti-fogging and water resistant performance of this film was tested. The film prepared by these 3 hydrophilic acrylates exhibited excellent hydrophilic anti-fogging performance. However, the water resistance becomes poor as hydrophilic monomer over 60%. A little fluoro-oligomer (<0.05%) was sufficient to prevent fogging. However, adding excess of fluoro-oligomer (>2%) may deteriorate the anti-fogging property of their films. In addition, the content of active dilutes, cross-linkers and photo-initiator play important roles in the anti-fogging and mechanical performance of their coatings.