Preparation And Properties Of Nanosilica Modified Waterborne Polyurethane Curing Agent

With the progress of nanotechnology, functional nanocomposites have been successfullyapplied to different fields, the dispersion of nanomaterials is the primary factor to realize itsspecial function. Polyurethane nanocomposites modified by inorganic nano-materials canobviously enhance the thermodynamic and mechanical properties, also presented somespecial properties, and thus it has became a major means of polyurethane modificationrecently. Nanocomposite prepared by isocyanate modified nanoparticles has been widelyused. Therefore, in this thesis, a series of polyurethane curing agents which were used toprepare2K WB-PURs have been obtained by the reaction of nanosilica and isocyanate, thenthe structure and properties of the film have been investigated.A series of nanosilica modified polyurethane curing agents (SG) have been obtainedwith nanosilica and hexamethylene diisocyanate trimer (HXR) as the raw materials,furthering a series of nanosilica modified waterborne polyurethane curing agent (WSG) wereprepared by using hydrophilic polyethylene glycol (PEG) to modify the SG curing agent. Theinfluences of the SiO2/HXR mass ratio, PEG contents, and the NCO/OH molar ratio on theproperties of the curing agents and the polyurethane film have been studied. The resultindicated that the SiO2at nanoform dispersed in SG and WSG, the hardness of the filmincreased1-2H, the flexibility、adhesion and impact resistance remain good, which clearlyreflected the enhance toughening function of nanosilica, also the thermostability of the2KWB-PURs film enhanced.A series of curing agents SWSiP were prepared from nanosilica-modified WSiP becauseof the excellent properties of2K WB-PUR film made from water-based silicon quitoisocyanate (WSiP) and a water-based acrylic resin. the influence of nanosilica on themechanical properties of the curing agents SWSiP and it’s2K WB-PURs have beeninvestigated. The results indicate that the2K WB-PUR film was flat and smooth, the surfacedrying fast and don’t gel surpass24h, the hardness of the film increased1-2H, the flexibility,adhesion and impact resistance remain good, thus offer a new idea and approach to prepare2K WB-PURs with excellent properties by making nanometer materials modifiedpolyisocyanate a water-dispersible polyisocyanate component. By contrast, the effect of nanosilica on the properties of the2K SB-PURs was validated.Firstly, a series of TMP-SiO2-modified polyurethane curing agents (SRG) have been obtainedwith (RG-2-60) formed by trimethylolpropane (TMP)-modified toluene diisocyanates (TDI)and nanosilica as the raw material, then PEG-TMP-SiO2-modified polyurethane agent (PSRG)were prepared by grafting PEG to the SRG curing agent, several different types of hydroxylacrylic resin were selected as hydroxyl component. The influence of the SG＆SRG on theproperties of the2K SB-PURs were explored. However, no prominent effect has been foundas we expected.