Preparation And Properties Of Heat-resistant 3D Printing Photosensitive Resin

Epoxy resin has been widely used in the field of UV 3D printing curing consumables in recent years,but it is difficult to meet the application requirements of SLA(Stereo Lithography Appearance)3D printing due to its shortcomings,such as high cross-linking density,high internal stress after curing,brittle quality,poor impact resistance and thermal stability.Therefore,it is great significance to toughen and strengthen the epoxy resin to improve its mechanical properties and heat resistance.In this paper,the commonly used bisphenol A type epoxy acrylate as the matrix,using organic and inorganic fillers to further modify the resin,in-depth study of the modified epoxy resin thermal stability mechanical properties and microscopic morphology.Firstly,the effects of diluent type and content,photoinitiator content and mass ratio of prepolymer to diluent on the properties of photosensitive resin materials were studied.A photosensitive resin with low viscosity and low curing shrinkage for SLA was prepared.The resin viscosity was 222.2 mPa-s and the curing shrinkage was 6.28%,which met the requirements of SLA-3D printing.An organosilicone intermediate was prepared by using isophorone diisocyanate(IPDI),hydroxy silicone oil and hydroxyethyl acrylate(HEA)as raw materials.The silicone modification of epoxy resin was realized by introducing-Si-O-group into the side chain of epoxy resin by chemical grafting method.The effects of organosilicon modification on mechanical properties,thermal stability and microstructure of epoxy resin were systematically studied.The results showed that the curing shrinkage of epoxy resin modified by organosilicon were obviously reduced and the printing precision were improved.In addition,the mechanical properties of the material was significantly improved,the impact strength and elongation at break were increased by 32.8%and 8.65%respectively,and the brittle fracture was transformed into ductile fracture,but the tensile strength of the material was decreased.The glass conversion temperature of modified epoxy resin was increased by 8.46℃,T50%and Tmax were increased by 1.9℃ and 6℃,respectively,indicating that the thermal stability of modified epoxy resin can be improved by organosilicate.A silane coupling agent γ-methylacrylloxy propyl trimethoxy silane(KH-570)was used to modify the surface of nano-sized TiO2,and the modified TiO2 was composite modified with epoxy resin modified by organosilicone.The effects of different addition amounts on the properties of organosilicone photosensitive resin materials were studied.The results showed that when the content of KH-570 reached 20%,which the dispersion of surface modified TiO2 was better,and the agglomeration phenomenon was obviously reduced.The tensile strength,impact strength and elongation at break were increased by 51.1%,43.8%and 10.8%,respectively,compared with the silicone modified resin when the addition amount of titanium dioxide in the system was 1.5%,and the hardness value was maintained at 81-83 HD.The thermal stability was also improved,T50%,Tmax and carbon residue rate were increased by 1.44℃,1.34℃ and 23.8%,respectively,compared with the silicone modified epoxy resin.The glass conversion temperature reached the maximum value when the addition amount was 2.5%,which was increased by 14.08℃ and 10.62℃,respectively,compared with the pure epoxy resin and the silicone modified resin.