Study On Synthesis Of Crosslinked Polyurethane-acrylate Hybrid Emulsion

The polyurethane emulsion has outstanding characteristic on film forming, and its film has a lot of excellent properties such as elasticity,high gloss, abrasion resistance and superior impact resistance at low temperature,but suffer from poor hardness,water and alcohol resistance. The polyacrylate polymer emulsion is lacking in film forming but its film possess excellent weather ability,hardness,and water and alcohol resistance. Crosslinked polyurethane-acrylate(PUA) hybrid emulsions possess good properties of polyurethane emulsion and polyacrylate emulsion together and avoid its disadvantages. But the water and alcohol resistance of the PUA film is still not good enough to suit the application of high-grade wood coatings. So,We have researched it in this article.Synthesis-crosslinked and self-crosslinked polyurethane-acrylate(PUA) hybrid emulsions have been synthesized. Polyurethane prepolymers were synthesized from toluene diisocyanate(TDI), polyether binary alcohol(N210), butanediol(BDO)and dimethytolpropionic acid(DMPA). Then,hydroxyl-ethyl methacrylate (HEMA) as a cross-linking agents used to introduce to the ends of the polyurethane molecular chains,after dispersed in water the polyurethane prepolymers copolymerized with vinyl monomers to synthesizing synthesis-crosslinked polyurethane-acrylate(PUA)hybrid emulsions;and(or) joined 3 Trimethylolpropane(TMP) in preparation process of polyurethane prepolymers to fabricate PU internal crosslinked hybrid emulsions. the polyurethane prepolymers dispersed in water,then adipic acid hydrazide(ADH) as a crosslinker chain extender introduce to the polyurethane molecular chains, with polyacrylate(PA) which got diacetoneacrylamide(DAAM) and glycidyl methacrylate(GMA) participate in its vinyl polymerization to synthesizing self-crosslinked polyurethane-acrylate(PUA) hybrid emulsions which crosslinked not only by ketone and hydrazide groups but also by epoxy and carboxyl groups.The Effects of ratio of -NCO/-OH,adding amount of DMPA and neutralization extent on polyurethane prepolymers. The Effects of ratio of TMP/PU,end capping reaction's temperature and time,ratio of HEMA/PU,adding amount of DBT and kind of polymerization inhibitor on the properties of synthesis-crosslinked emulsions and its films were discussed in details.According to change adding amount of GMA,DAAM,ADH and mol ratio( DAAM:AHD) respectively,we carefully studied their efects on the properties of self-crosslinked emulsions and its films.The structure and performance of the noncross-linked type emulsion and the two kinds of crosslinked type emulsions were examined and analysised. The Fourier transform infrared(FTIR) spectrum analysis proved that the crosslinking reaction occurs indeed.The emulsions was characterized by the laser light scattering particle size analysis. The test results indicated that particle sizes of the noncross-linked type emulsion,synthesis-crosslinked emulsion and the the self-crosslinked emulsion are respectively about 90nm,95nm,100nm. The thermogravimetry(TG) and the scanning electron micro-scope(SEM) analysis indicated the thermal stability and the surface density of the double self-crosslinking PUA film. Crosslinked type emulsion's hardness and water resistance better than these of noncross-linked type emulsion's evidently.