Study On New Photocurable Systems Suitable For 3D Printing

In recent years,with the increasing demand for personalized and customized products,photocurable 3D printing technology has attracted more and more attention due to its advantages such as fast molding speed and convenient operation,and has been widely used in aerospace,biomedical,energy and power fields.In the process of photocurable 3D printing,the photocurable resin system is the key factor affecting the quality of the final printed product,so it is of great significance to study.At present,the commercial types of photocurable resin products are relatively rich,but the present photocurable resin products still have problems,such as low dimensional accuracy and poor mechanical properties.In addition,many applications of UV curing 3D printing require materials with various special functions,such as high printing resolution,high light transmission,high elasticity,good biocompatibility and so on.Therefore,on the basis of the existing 3D printing photocurable resin,further improve the performance and develop new 3D printing photocurable material system research is still promising.In this article,vinyl ether cationic photocurable system,acrylate modified free radical photocurable system and free radical-cationic hybrid photocurable system were studied.In the study of vinyl ether cationic photocurable system,vinyl ether monomers were selected as the main component of the system.Aryl onium salts are cationic photoinitiators for the polymerization of vinyl and epoxide.The commonly used aryl onium salt photoinitiators have their principal absorption bands in the short wavelength(220–310 nm)region of the UV spectrum.However,the exposure source of 3D printing is generally 365 nm or 405 nm,which leads to low initiation and polymerization rate of vinyl ethers,so they are rarely used in the application of UV curing 3D printing.It has been reported that by using the combination of hydrogen abstraction free radical photoinitiators and a diaryliodonium salt,long wavelength UV and visible light can be used to photoinitiate cationic polymerization.We studied the polymerization rate of the vinyl ether monomer by using p-(octyoxyphenyl)phenyliodomium hexafluoroantimonste as cationic photoinitiator and 2-isopropylthioxanthone as hydrogen abstraction free radical photoinitiator.It was shown that photopolymerization of vinyl ether monomer could be efficiently carried out at 365 nm UV light under the assistance of hydrogen abstraction free radical photoinitiators.In order to further regulate the properties of the system,the dosage of additive agents in the system was quantitatively studied and the proportion of each component in the system was determined.Then,the curing thickness measurement showed that the thickness of the photocured film material could be as low as 30 ?m,which is beneficial to improve the printing longitudinal resolution of the system.The polymerization rate test proved that the system could be polymerized quickly in a short time,which is beneficial to improve the printing efficiency.In addition,the thermal stability test,viscosity test and the photocurable 3D printing test proved that the system could be used to print fine structures on the micron scale.In the acrylate modified free radical photocurable system,high strength photocured materials and high transparency photocured materials were obtained respectively by the combination of different free radical monomer materials.The tensile strength test and Shore hardness test showed that the tensile strength of the high strength UV cured material reached 61 MPa,and the Shore hardness was 62 HD.Through the viscosity test,it was found that the viscosity of the system was only 9.66 m Pa·s,which can help improve the printing efficiency.Through the light transmittance test,it was found that the light transmittance of two kinds of high transparent photocurable materials reached 93% and 90%,respectively,which proved the excellent light transmittance of the two kinds of light-curable materials.In the study of free radical-cationic hybrid photocurable system,the mechanical properties of the cured hybrid system were mainly explored.On the one hand,a hybrid system with high elongation at break was obtained,and the elongation at break of the system was up to 37%.On the other hand,a hybrid system with good mechanical properties was also obtained.The tensile strength and Shore hardness tests showed that the tensile strength of the system reached 40 MPa and the Shore hardness was 62 HD.Then,the influence of post-curing temperature and post-curing time on the mechanical properties of the system were investigated.It was found that the post-curing temperature and post-curing time did not significantly improve the tensile strength of the system,but had a great influence on the elongation at break of the system.