Research On Preparation,Performance And Pplication Of Waterborne Polyurethane

Waterborne polyurethane(WPU)uses water as the solvent and contains no or only a small amount of organic solvents.The molecular structure can be highly regulated by adjusting the ratio and type of soft and hard segments.It has been widely used in coatings,adhesives,surfactants,inks,biomedicine and other fields.Based on the WPU emulsion preparation process experiment,using the structure-activity relationship research principle,this subject successfully developed a series of waterborne polyurethane dispersants suitable for pesticide suspensions,and studied its application in pesticide SC.The main research results of this paper are as follows:1.A series of WPU emulsions were prepared by the method of prepolymer dispersion,and the synthesis process of WPU emulsion was successfully optimized by careful study of some key factors such as temperature,the amount of key raw materials,R value,and the type of post-chain extender.At the same time,the properties of films prepared under different emulsions were investigated.The results showed that when the prepolymerization temperature is 75°C,the emulsification temperature is 30-40°C,the amount of catalyst is 0.05%,and the R value is 1.75,the WPU emulsion prepared by TETA chain extension had the best overall performance.The prepared product had a particle size of nanometer level and a solid content of up to 40%.The prepared film exhibited good performance in terms of resistance to water,acid,alkali,and salt.2.Using the preparation method and technology of polyurethane dispersion for reference,by adjusting the amount of DMPA and capping with PEG of different molecular weights,PUDs with bistable effects(electrostatic repulsion and steric hindrance)were prepared and characterized,At the same time,some basic properties of PUDs(surface tension,HLB value,emulsifying properties)are studied.The results showed that: PUD8-600 has the lowest surface tension,which is 38.77 m N/m.Compared with PUD5-600,the HLB value and emulsification time of the other three dispersants are larger.3.Four PU dispersants designed and synthesized are applied to 430 g/L Tebuconazole SC.At the same time,by testing some basic properties of SC(particle size,Zeta potential,SEM,suspension rate,rheological properties,specific absorbance,etc.),the physical stability of SC under different dispersants was studied,and the optimal dosage of PU dispersant was probed.And discussed its dispersion mechanism.The results showed that the dispersion stability of SC prepared by PUD8-800 is the best,and the best amount of dispersant is 4wt%.The analysis of the results showed that appropriately increasing the content of DMPA is beneficial to improve the dispersion stability of SC,and it also showed that the hydrophilic segment needs to be maintained at an equilibrium value to create better dispersion stability.