Preparation And Development Of UV-curable Electronic Paste For 3D Inkjet Printing

Three-dimensional inkjet printing is a subdivision technology of additive manufacturing.Compare to other additive manufacturing technology,it is much more active for the advantages of good flexibility,well-targeted,and multi-materials one piece manufactured.The chief applications are restricted in the biological medical aspect,such as denstistry and organs printing,owing to the development of materials is immature and the equipments is expensive.This technology still has numerous difficulties need to face and our task is mainly aimed at the development of UV-curable electronic paste used for this technology.We have studied following areas and some progress has been made.UV-heat dual curable resin was prepared by modifying epoxy resin with acrylic acid without eliminating oxygen and atmosphere protecting.The resins were characterized by infrared spectroscopy,the results proved that the resins obtained were the target ones.The effects acrylic acid content,reaction temperature on the physical properties such as flexibility,impact resistance,and reagent resistance were studied.It was found that there was a great influence of acrylic acid content and reaction temperature on the performance of the resins,this shows the importance of reaction conditions.Coatings of the resin were characterized by infrared spectroscopy,the results proved that the curing method of UV curing combined with thermocuring was helpful to cut down curing time and improve the curing degree.The results showed that controle reaction conditions in a reasonable range could obviously improve the curing property of the resin and the the physical properties of the cured films,particularly on the hardness and flexibility.Because of the change of reaction conditions will lead to the structure change of the resin.The UV-heat dual-curable resin obtained hereinbefore was mixed with magnetic powder(MP)to make magnetic pastes of different formulations.Influences of diluents,thixotropic agents,and MP content on the rheology,stability and the UV-curing behavior of the pastes and hardness and adhesive force of the cured films were studied.The results showed that when the resin: PGMEA=1:2.5,peoformances of the paste was the best and the viscosity meets the demand.Thixotropic effect was more apparent when the thixotropic agent is activated and pre-dispersed and the best dosage is 1 %(wt).The paste could be still used for 3D inkjet printing when the solid loading increased to 65 %(wt)and the performances of the cured film held steady.The properties of the cured film will decline sharply as the MP content still increasing.The density and magnetic energy product of the cured parts were measured by Archimedes drainage method and permanent magnetic characteristic measuring instrument,respectively.The results showed that controlled the MP content in a reasonable range could ensure the compactness of the parts.The MP was modified by surface modification agent with different properties and prepared magnetic pastes with the modified MP.The viscosity of the pastes and dispersion effect of MP were characterized by rotational rheometer,the combine effect of MP and resin of the cured parts were characterized by scanning electron microscope.The results showed that an appropriate surface modifying to the MP could improve its dispersion effect,viscosity of the paste,and properties of the cured parts obviously.It was better to cooperated use surface modification agents for each agent is one-sidedness.