Study On Low Viscosity & Fast Curing 3DP Materials Based On Spray Process

UV-curing three-dimension printing(3DP) possesses high precision and low-cost in production, which has been widely used in aerospace, entertainment lifestyle, medical treatment and so on. Currently, there are some problems in the UV-curing materials such as high viscosity and slow curing, which directly affect the precision and efficiency of UV-curing 3DP production. In this paper, two kinds of epoxy acrylate oligomers and one kind of urethane acrylate monomer were synthesized. The UV-curing materials were prepared by the synthetic products, monomer and photo initiator. The properties of 3DP UV-curing materials before and after cured were studied.Firstly, the polyethylene glycol diglycidyl ether diacrylate(R1) and ethylene glycol diglycidyl ether diacrylate(R2) were synthesized. The optimum synthesizing conditions were as below: the mole ratio of acrylic acid to glycidyl ether was 2.1:1, the reaction temperature was 100 oC, the reaction time was 6.5h, the mass fraction of triphenylphosphine was 0.7% and the mass fraction of hydroxy benzene methyl ether was 0.2%. The UV-curing materials were prepared by prepolymer(R1 and R2), trimethylolpropane trimethylacrylate(TMPTA) and photo initiator 369. The results showed that the viscosity of UV-curing materials before cured was below 300 m Pa·s. The curing speed of UV-curing materials was both above 14m/min. The volume shrinkage of UV-curing materials after cured were 11.3% and 7.6% respectively, the hardness of UV-curing materials after cured was 4H. Therefore, R1 was determined as prepolymer of 3DP UV-curing materials.The polyurethane acrylate(NIPUA) monomer with three functional groups was synthesized by the method of isocyanate. The optimum synthesizing conditions of NIPUA were as follows: firstly, the methyl carbamate(NIPU) was prepared under molar ratio 1:1 of ethylene carbonate to dietlianolamine, at 80 oC for 5h, then the NIPUA was prepared under molar ratio 2.1:1 of NIPU to acryloyl chloride, at-5oC for 5h. The UV-curing materials were prepared by NIPUA, R1, monomer TPGTA and photo initiator. The results showed that when the mass fraction of NIPUA and tripropylene glycol diacrylate(TPGDA) were 10% and 20% respectively, the UV-curing materials possessed the optimal properties. The viscosity of the UV-curing materials before cured was 185 m Pa·s. The hardness, initial decomposition temperature and residual rate of the UV-curing materials after cured were reached to 4H, 310 oC and 10wt%, respectively. The curing speed of the UV-curing materials was 15.9m/min.Finally, the photo initiator system of UV-curing materials was studied. The results showed that the curing speed of the UV-curing materials was promoted when the photo initiators of 369 and ITX were added to the UV-curing materials because of effective use of UV energy. Meanwhile, the oxygen inhibition could be prevented. The UV-curing materials were prepared by R1, NIPUA, TPGDA, photo initiator 369 and ITX. The UV-curing materials possess the optimal properties when the mass ratio of 369 to ITX was 1:1 and total content was 3wt%. The viscosity the UV-curing materials before cured was 190 m Pa·s. The hardness of the UV-curing materials after cured was 6H, the initial decomposition temperature of the UV-curing materials after cured was 314 oC. The curing speed of the UV-curing materials was 19.2m/min, the degree of cure of the UV-curing materials was more than 98%. This UV-curing materials formulation can meet the demands of UV-curing 3DP.