Preparation Of Waterborne Polyurethane Composite Film And Its Application In 3D Printing

The fused deposition modeling（FDM）technology is a rapid prototyping method used in3D printers.It has the advantages of simple operation,strong processability,short time-consuming and low cost,but the shortcomings such as low precision and weak impact resistance limit the application in the field of offshore equipment processing.Protecting the surface can not only reduce surface defects,but also improve the surface toughness and safety factor of the printing products.Waterborne polyurethane（WPU）,a green protective coating,has been used as surface protection material widely.However,due to the introduction of hydrophilic chain extender and lack of cross-linking,the traditional WPU has problems such as poor waterproof and insufficient mechanical properties.Therefore,the aim of the paper is the preparation of WPU materials with comprehensive properties and their application in surface protection of FDM printing products.Firstly,the poly（3,3,3-trifluoropropylmethylsiloxane）/waterborne polyurethane（PTFS/WPU）composite films was prepared by introducing PTFS by chemical copolymerization in a WPU system.The test results show that with the increase of PTFS content,the tensile strength of PTFS/WPU composite films increases first and then decreases,while the change trend of elongation at break is opposite,and the water resistance increases.Although PTFS promotes the tensile strength of WPU composite films,it also reduces the toughness of the material and does not simultaneously achieve the effect of strengthening and toughening.The treatment of the surface of WPU films with fluorosilane solution not only enhances the hydrophobicity of WPU composite films,but also improves the mechanical properties of the composite films,but still can not meet the actual demand.In order to improve the mechanical properties and waterproof of WPU films at the same time,the halloysite nanotubes/waterborne polyurethane composite films were prepared by in-situ polymerization and surface fluorination method,and the content and surface of aminated halloysite nanotubes（AHNTs）were investigated.Effect of fluorination on the properties of halloysite nanotubes/waterborne polyurethane（AHNTs/WPU）composite films.The results reveal that the mechanical properties and heat resistance of AHNTs/WPU composite films increase first and then decrease with the increase of mass ratio of AHNTs,and the waterproof is improved.When the mass ratio of AHNTs is 1.5%,the composite filmss has better comprehensive properties.Compared with the pure waterborne polyurethane films,the tensile strength,elongation at break and initial decomposition temperature(T_d5)of the AHNTs/WPU composite films were increased by 50%,35%and 9°C,respectively..The water absorption of the composite films was reduced from 12.3%to 5.8%,the water contact angle is increased from79°to 95.1°.After surface fluorination treatment,the water contact angle of the AHNTs/WPU composite films increased to 114.5°,which exhibited better hydrophobicity.The effect of the FDM print parameter（filling rate and filling pattern）on the performance of the printed sample was then investigated.The results display that the mechanical properties of the sample are proportional to the filling rate;the concentric circle pattern filling sample has the good water absorption and.highest mechanical propertiesIn summary,the two kinds of composite emulsions with the best comprehensive performance of PTFS/WPU and AHNTs/WPU were selected,and the line and concentric circle pattern filling samples were surface-protected by painting.The reduce of water absorption and the improvemt of tensile strength of the sample after protection proves the practicality of self-made WPU composite emulsion and provides the reference for the application of FDM technology in the field of marine equipment manufacturing.