Preparation Of 1,5-bis[(3-ethyl-3-methoxyoxetane)propyl]-hexamethyltrisiloxane And Research On Its UV Curing Properties

UV-curable coatings are widely used in coating,bonding agent and other fields due to its advantages of fast curing rate,low energy consumption and environmental friendly.However,the problems of few types of polymerized monomers and low reactivity have become the main factors restricting the development of UV-curable coatings.In order to develop a novel cationic photosensitive resin with low viscosity and high photosensitivity,3-ethyl-3-allylmethoxyoxetane(EAMO)was used to react with 1,1,3,3,5,5-hexamethyltrisiloxane(HMTS)to obtain a new monomer1,5-bis[(3-ethyl-3-methoxyoxetane)propyl]hexamethyltrisiloxane(HMBEMOPTS).The UV-curing properties of the new monomer were studied,and finally it was used for stereolithography 3D printing to prepare some samples for test.The specific research contents are as follows:(1)First,3-ethyl-3-hydroxymethyloxetane(EHO)was synthesized by the reaction of trihydroxypropane and diethyl carbonate.Then using tetrabutylammonium bromide as a catalyst,EHO was polymerized with allyl bromide to obtain EAMO.The influence of reaction conditions on the reaction were studied,the experimental results showed that the yield of EAMO was the highest when the molar ratio of EHO to allyl bromide was 1.0:1.2,the reaction temperature was 0℃,and the reaction time was 24h.The molecular structure of the product was confirmed by FT-IR and~1H-NMR,and it was confirmed that the obtained product was EAMO.(2)EAMO and HMTS were used as raw materials to synthesize HMBEMOPTS when Karstedt was used as catalyst and toluene was used as solvent.The influence of reaction conditions on the reaction were studied,the experimental results showed that the yield of HMBEMOPTS was the highest when the molar ratio of EAMO and HMTS was 2.2:1,the reaction temperature was 90℃,the reaction time was 12h,and the amount of Karstedt was 0.3%.The molecular structure of the product was confirmed by FT-IR and ~1H-NMR,and it was confirmed that the final product was the target product HMBEMOPTS.(3)Added photoinitiator triarylsulfonium hexafluoroantimonate UVI-6976 to HMBEMOPTS to prepare a novel cationic UV-curing system.The viscosity test shows that the viscosity of the synthetic monomer is only 13m Pa·s at room temperature,and its flow performance is good;the thermogravimetric analysis shows that the decomposition temperature of the synthetic monomer is 243.6℃,and when the temperature reaches 368.2℃,the thermal weight loss of the sample reaches 50%;p-DSC thermal analysis shows that the photosensitivity of the synthesized monomer is better than that of 3,3’-(oxybismethylene)bis(3-ethyl)oxetane and epoxy resin E-51,it proves that the photosensitive properties of oxetane can be effectively improved by siloxane modification;HMBEMOPTS,epoxy resin E-51 and photoinitiator UVI-6976 were blended to prepare a cationic photosensitive resin,and the mechanical properties were tested after curing.The experimental results show that when the mass fraction of HMBEMOPTS in the blended resin is 10%and 50%,respectively,the blended resin has the best tensile properties and paint film properties,and its tensile strength,elongation at break,paint film impact properties and the film flexibility are 23.07MPa,2.88%,40kg·cm and 2mm,respectively.(4)A new type of photosensitive resin was prepared with HMBEMOPTS,UVI-6976 as the cationic photoinitiator,and some additives for stereolithography 3D printing.Experimental results show that when the system temperature,laser power,and scanning speed are set to 30℃,150m W,and 3000mm/s,respectively,the printed samples have good precision and mechanical properties.The tensile strength,tensile modulus,elongation at break,impact strength and flexibility of the printed samples are 25.8MPa,360.4MPa,4.6%,40kg·cm,and 2mm,respectively.The transverse and longitudinal shrinkage of the printed samples are 1.95%and 2.02%,respectively,with good dimensional stability and good solvent resistance.