Study On Modification And Performance Of SLA-3D Printing Photosensitive Resin

As a kind of high forming accuracy technology,SLA(Stereo lithography appearance)possesse outstanding properties,including higher forming accuracy,clear shapes and soft surface.Presently,the preparation of molded parts by SLA technology mainly faces with problems includin g high viscosity of the resin system,poor mechanical properties of the printed parts,high shrinkage and high cost.Therefore,developing high-performance,low viscosity,low shrinkage and low cost photosensitive resin are the keys to solve SLA technology problem.Based on free radical photocuring system,epoxy acrylate(EA)and urethane acrylate(PUA)were used as oligomers in this paper.The effect of mass ratio of oligomers,photoinitiator content,diluent type,diluent content influence on the performance of 3D printing photosensitive resin materials were studied,aiming to prepare SLA-3D printing photosensitive resin with low viscosity,good m echanical properties and low shrinkage was prepared.Silane coupling agent A151 was used to modify the surface of nano Al2O3 with different particle diameters.And modified nano Al2O3 with the 3D printing photosensitive resin were mechanically mixed to enhance the modification,investigating that the effect of different modified nano Al2O3 particles diameter,different addition amount and different particle size of Al2O3 compound on viscosity,mechanical properties,shrinkage and thermal stability of photosensitive resin material.The results showed that,200 nm Al2O3 presented better mechanical properties and shrinkage after curing compared with 50 nm Al2O3.However the thermal stability is slightly worse than 50 nm Al2O3.The outcome of Al2O3 compound modified photosensitive resin with different particle size was better than single component modification.When the prototion of Al2O3 compound modified photosensitive resin was 0.6:2.4(50 nm:200 nm),the photosensitive resin 3D printing material presented remarkable properties,with 52.36 MPa tensile strength,33.11%fracture elongation,10.12 kJ/m2 impact strength,85.5 HD hardness.In order to reduce the viscosity and shrinkage of 3D printing photosensitive resin,silane coupling agent A174 and distilled water was used as raw materials to prepare hyperbranched polysiloxane(HBPSi)by hydrolysis under acidic conditions,and the prepared HBPSi was mechanically blended with photosensitive resin,aiming to modifying free radical 3D printing photosensitive resin.The effects of different amounts of HBPSi on the viscosity,mechanical properties,shrinkage and thermal stability of 3D printing photosensitive resins were studied.The results showed that when the molar ratio of A174 and distilled water was 1.2:1,the reaction time was 3h,the viscosity of the prepared HBPSi was lower than 1000mPa·s.When the amount of HBPSi added is 5%,the mechanical properties of the photosensitive resin 3D printing material were best.The tensile strength was 29.62 MPa,the elongation at break was 32.8%,and the impact strength was 7.83 kJ/m2.When the amount of HBPSi added is 25%,the volume shrinkage and linear shrinkage of the 3D printing photosensitive resin material reached the minimum value,5.38%and 0.63%respectively.Meanwhile the T50%of the photosensitive material increased to 22℃.