Preparation Of A Novel Dioxetane Derivative And Its UV Curing Properties

UV-curing materials generally consist of prepolymer,UV-curable initiator,and diluent.The prepolymers that can be used for cationic photocuring are mostly phenolic epoxy resins,bisphenol A epoxy resins,alicyclic epoxy compounds and heterocyclic epoxy compounds.In this paper,a new kind of cationic UV-curable reactive monomer:difunctional oxetane modified by silane was synthesized.The difunctional oxetane modified by silane was highly reactive in the cationic photocuring system.The specific research of this paper is as follows:Firstly,the monofunctional oxetane was synthesized with Trimethylolpropane and Diethyl carbonate as raw materials,potassium hydroxide as catalyst and methanol as solvent.The optimal parameters of the reaction were discussed.Accroding to the process of the experiment,the optimum synthesis conditions were determined:the molar ratio n(diethyl carbonate): n(trimethylolpropane)= 1:1 when the amount of diethyl carbonate was 0.2 mol,the amount of KOH was 0.1 g,and the amount of methanol was 3 ml.The temperature of the reaction was 115°C and the time of the reaction was 1 h.Secondly,the allyl oxetaneunder was synthesized in the Potassium hydroxide alkaline solution,with monofunctional oxetane obtained in the first step and allyl bromidethe as raw materials,and tetrabutylammonium bromide as a phase transfer catalyst..Accroding to the process and results of the reaction,the optimum synthesis conditions of the reaction were determined:n(allyl bromide): n(3-ethyl-3-hydroxymethyloxetane)=1.4:1,m(3-ethyl-3-hydroxymethyloxetane):m(tet rabutylammonium bromide)= 23.2:1.The temperature of the reaction was 0 °C and the time of the reaction was 24 h.Thirdly,the final silane-modified difunctional oxetane was synthesized with the synthesized allyl oxetane and 1,4-bis(dimethylsilyl)benzene as raw materials,and the transition metal tris(triphenylphosphine)rhodium chloride as the catalyst.The best conditions of the synthesis were determined accroding to the process and the final results of the reaction:n(allyl oxetane):n1,4-bis(dimethylsilyl)benzene=2:1,the amount of catalyst was 0.4%.Finally,a kind of cationic UV curing system was got by mixing the silane-modified difunctional oxetane,E-51(Bisphenol A epoxy resin)and UV-6976 in a a certain proportion.The parameters of the light curing process and the properties of the materials with different proportion were also tested and analyzed.