| The ideal function of photoinitiators include high absorption in the emission spectrum of the lamp,good solubility in the formulation process,high quantum yield,high photoreactivity,low odor,low toxicity,there is no residue in the yellowing polymer during migration,and the storage stability is good.Based on the above criteria,current commercial small molecular weight photoinitiators are not satisfactory.The development and application of multi-functional macromolecular photoinitiators is currently the development trend in the field of photocurable coatings.Because of its low volatilization,low migration,low toxicity,etc.,it is in line with the environmental protection concept of green energy development.In this paper,a series of novel polyfunctional macromolecular photoinitiators were prepared by the application of polyfunctional photoinitiators in the field of UV curable materials,using acid chloride reaction,esterification reaction and other reaction means.A series of photoinitiators were added to the photocurable formulation system to study their optical and mechanical properties.The main research is as follows:1)A tetrafunctional pentaerythritol tetrabenzoate photoinitiator(PTF)was synthesized based on a benzoylformate photoinitiator.It was characterized by infrared spectroscopy,nuclear magnetic resonance and mass spectrometry and other way.UV-visible spectroscopy and Photo-DSC patterns show that it has strong UV absorption capacity and good photopolymerization activity.The properties of PTF,2-hydroxy-2-methyl-phenylacetone(Darocur 1173 photoinitiator)and resin and monomer to form a photocurable coating were investigated.The thermal stability of the PTF photoinitiator is superior to the 1173 photoinitiator.This is mainly because PTF is a pyrolysis photoinitiator with the characteristics of pyrolysis photoinitiator.The concentration of active radical generated after photolysis is higher than that of1173 light.The rate at which PTF initiates TMPTA polymerization is higher.Under the same experimental conditions,the mobility of the PTF system is only 5% of the 1173 system photoinitiator,which indicates that the PTF macromolecular photoinitiator containing polyfunctionality can effectively fix the coating in the cured film,thereby greatly reducing the migration of the cured film.2)A polymerizable photoinitiator bis(2-(4-(2-hydroxy-2-methylpropanoyl)phenoxy)ethyl)-2-methylene succinic acid(IAHHMP)was successfully synthesized by direct esterification.The IAHHMP was characterized by infrared spectroscopy,nuclear magnetic resonance,mass spectrometry and the like.UV-visible spectroscopy and Photo-DSC patterns show that it has strong UV absorption capacity and good photopolymerization activity,and is an effective free radical photoinitiator.IAHHMP,1-hydroxycyclohexyl phenyl ketone(Irgacure 184 photoinitiator),2-hydroxy-2-methyl-p-hydroxyethyl ether phenyl acetonone-1(Darocur 2959 photoinitiator)were studied.The resin and monomer constitute the properties of the photocurable coating.Thermogravimetric analysis showed that the temperature loss of IAHHMP 5% and the final weight loss were higher than 184 photoinitiator by more than 100 °C,and the thermal stability was better.The extraction experiment showed that the mobility of IAHHMP photocuring system was only 184 photocuring system.11.90%.Excellent high temperature resistance and low mobility make the IAHHMP polymerizable photoinitiator as an ?-hydroxyketone derivative have a development prospect for various food packaging materials.3)The macromolecular photoinitiator 1,2-bis(2-(4-(2-hydroxy-2-methyl-propionyl)phenoxy)ethyl)was synthesized on the basis of commercial 1173 and 2959 photoinitiators.4-(2-Methyl-1-oxo-1-phenylpropan-2-yl)benzene-1,2,4-tricarboxylate(HTH),which was determined by infrared spectroscopy,nuclear magnetic resonance,mass spectrometry and the like.The UV-visible spectrum and Photo-DSC pattern showed that it has strong UV absorption ability and good photopolymerization activity,it is an effective free radical photoinitiator.The properties of HTH,1173,and 2959 photoinitiators and resin monomers to form photocurable coatings were investigated.The thermal stability of the HTH photoinitiator is slightly higher than the 2959 photoinitiator.The photoinitiating activity of HTH is higher than that of the 1173 photoinitiator,indicating that the HTH photoinitiator has the performance characteristics of the ?-hydroxyketone photoinitiator.This is mainly due to the fact that the concentration of active radicals produced by HTH after photolysis is higher than that of 1173 photoinitiators,so that the rate at which HTH is initiated by TMPTA is higher.Under the same experimental conditions,the mobility of the HTH system is only 41.80% of the photoinitiator of the 2959 system,and the mobility of the HTH system is only 20.65% of the photoinitiator of the 1173 system,indicating that the HTH macromolecule containing polyfunctionality is photoinitiated.This indicatesthat the HTH macromolecular photoinitiator containing a polyfunctionality can effectively fix the coating in the cured film,thereby reducing the migration of the cured film. |
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