Synthesis And Characterization Of Flame Retardant Modified Waterborne Polyurethane

Waterborne polyurethane has excellent adhesive ability,good wear resistance,chemical resistance,excellent heat resistance performance,good low temperature resistance,good biocompatibility,and the characteristics of environmental non-toxic,therefore,it is widely used in furniture auto refinish coatings,textile coating,leather finishing,industrial coatings,grouting materials and car interior and broad field such as medicine carrier.But water-based polyurethane in the coating process water analysis of slow,film-film resistance,polyurethane flammability,fire hazard and other deficiencies.Phosphorus-containing flame retardant has a dual effect of plasticizing and flame retardant,it gives excellent flame retardant properties,and that,when burned,the smoke less than of phosphorus-containing flame retardants,accord with the requirement of people to the environment.Nanometer silicon dioxide can be used for hydrogen bonding with polymers,with nano-silica modified waterborne polyurethane.On the one hand,it can obtain new functions of polyurethane materials.On the other hand,it can improve the mechanical properties and thermal stability of waterborne polyurethane.In this paper,polypropylene glycol(PPG),isophorone diisocyanate(IPDI)as the main raw material to synthesize polyurethane pre polymers,dihydroxy methyl propionic acid(DMPA)as hydrophilic chain extender,with triethylamine(TEA)as a salt,1,4 yiding diol(BDO)is a small molecule chain extension agent,using anionic emulsion synthesis of waterborne polyurethane emulsion.The synthetic waterborne polyurethane is indicated by FTIR.Eigen modified waterborne polyurethane with phosphorus-containing flame retardant,phosphorus monomer dihydroxy methyl oxidation of phosphorus and chain extender 1,4-butanediol compound with join reaction system,according to different proportions to get flame retardant waterborne polyurethane emulsion.Through the oxygen index,cone calorimeter test the flame retardancy of polyurethane film,thermal stability by thermogravimetric analyzer test kits,by scanning electron microscope the combustion section,through the EDS and infrared analysis of the flame retardant mechanism of carbon residue.Results show that after joining dihydroxy methyl oxidation of phosphorus,the limit oxygen index of composites is improved,and when the dihydroxy oxide was 1.12%,the oxygen index was the highest,reaching 27.8%,compared to not join the limit oxygen index of waterborne polyurethane,increased by 54%.After the addition of dihydroxymethyl oxide,the thermal stability of composite materials improved.This experiment adopts a Y ammonia propyl triethoxy silane(KH-550)to modification of nano SiO2,will be modified with different content of silica nanoparticles dispersed in PPG,reaction with IPDI,get different content of nano silicon dioxide composite waterborne PPG,reaction with IPDI,get different content of nano silicon dioxide composite waterborne polyurethane emulsion.The composite materials were characterized by measuring the particle size,viscosity and stability of composite emulsion and the absorption rate,thermal weight,mechanical property and scanning electron microscope.The scanning electron microscopy of the composite membrane can be seen that when the content of SiO2 is 3%,the nanoparticles are dispersed uniformly,and there is no large-scale clustering phenomenon.The addition of modified modified nano-SiO2 caused the tensile strength of the water-based polyurethane film to decrease after the increase of the tensile strength of the film.The elongation of the fracture elongation was decreased and the trend of the increase was decreased.When the content of nano-SiO2 was 2%of the prepolymer quality,the tensile strength reached a maximum of 34.55 MPa.The addition of modified nano-SiO2 has reduced the water absorption rate of waterborne polyurethane film.With the increase of the quality fraction of nano-SiO2,the absorption rate of polyurethane film was reduced first and then increased.When the content of nanometer SiO2 was 3%,the water absorption rate was 15.85%.