Synthesis And Performance Study Of New HMPP-type Photoinitiators

With excellent properties of efficiency and environmental friendliness,photo curing technology has been wildly used in coatings,adhesives,inks and printing.In this paper,the existing problems and the development trend of UV curing are analyzed based on reviewing the development of UV curing technology and photoinitiators.Aiming at the problem of oxygen inhibition and migration of residual photoinitiator,a series of novel pyrolysis type photoinitiators were designed and synthesized,and the mechanism of hydrogen transfer type photoinitiator was preliminary discussed.The main research works and achievements were described as following:The polymerizable photoinitiator HEMA-IPDI-2959 was prepared by the reaction of isophorone diisocyanate with Irgacure 2959 and 2-hydroxyethyl methacrylate.The structure and photo bleaching progress of HEMA-IPDI-2959 were characterized by IR,¹H NMR,UV-vis and MS.The results of UV curing kinetics of polymerization showed that the HEMA-IPDI-2959 has better activity than Irgacure 2959.The migration rate of HEMA-IPDI-2959 was only 18%of that of Irgacure 2959.The fluorinated photoinitiators 2959-IPDI-F,2959-IPDI-F-HDDA and 2959-IPDI-F-?PO₃-TMPTA?were synthesized by the reaction of perfluoroalkylethyl acrylate,1,6-hexanediol diacrylate,propolylated trimethylolpropane triacrylate with amine modified Irgacure 2959.2959-IPDI-PFA was synthesized by the reaction of perfluoroalkylethyl,Irgacure 2959 and isophorone diisocyanate.The structures and photo bleaching progress were characterized by IR,NMR,UV-vis and MS.The kinetics of polymerization showed that the fluorinated photoinitiators has better anti oxygen inhibition,and the UV initiated activity was in the order of 2959-IPDI-F-HDDA/2959-IPDI-F-?PO₃-TMPTA?>2959-IPDI-F?2959-IPDI-PFA>Irgacure 2959+PFEA>Irgacure 2959.When all the materials was mixed evenly,the static setting was favorable for the migration of the fluorinated photoinitiator to the surface.The XPS analysis of cured polymer illustrated that the distribution of fluorine was gradient.The migration of fluorinated photoinitiator to the surface resulted in higher concentration of initiator on the surface.The higher curing rate at the surface caused a large amount of wrinkles on the surface.The obtained fluorine-rich film surface has a certain degree of hydrophobicity.Long alkyl chain modified HMPP-type macrophotoinitiators 2959-IPDI-Am and2959-IPDI-Al had been synthesized through the reaction of Irgacure 2959,isophorone diisocyanate and octadecylamine or octadecanol.The structures and photo bleaching progress were characterized by FT-IR,¹H NMR and UV-vis.The dynamics of polymerization showed that 2959-IPDI-Am and 2959-IPDI-Al have excellent photo initiated activity,and the oxygen inhibition effect can be reduced in a certain degree.The structure of photopolymerization production of butyl acrylate initiated by benzophenone/ether was characterized by NMR and MS.Under irradiation of UV light,benzophenone absorbed the UV energy to be activated,and the hydrogen transfer between activated benzophenone and diethylene glycol?DEG?to form two kinds of radicals.The radicals on the diethylene glycol would initiate the radical addition to butyl acrylate,forming monomer radical.This monomer radical could undergo the hydrogen transfer to form new radical,which back to the DEG main chain,the obtained new radical may still initiate the chain growth.The radical was likely walking along the DEG chain,forming multiple reactive points at DEG chain,which resulted in forming DEG supported substituted poly butyl acrylate.