Synthesis And Application On The Soft Segment And Hard Segment Co-modified Halogen-Free Flame-retardant Waterborne Polyurethane

With the advent of technology,waterborne polyurethanes are widely applied in coating material in recent years,such as leather,wood,textile,etc,which can significantly improve the gloss,hardness,flexibility,and water resistance.Researchers have known that flame-retardant waterborne polyurethanes are applied in coating processing,which can significantly improve the flame retardant of fabric.At present,fabrics were mostly treaded by water-based polyurethane added flame retardant on the market,with the defects of opaque coating,adding a large amount of fire retardant,poor washing and easy migration.Reactive flame retardant water-based polyurethane can overcome these shortcomings.It can significantly increase the flame retardant of fabric,while not affect the other application performance of fabric.With the aim to prepare flame retardant and environment friendly textile,this paper focused on the synthesis,characterization and application properties of soft segment and hard segment co-modified halogen-hree flame-retardant waterborne polyurethane.In this study,we first designed and developed a novel diamine with cyclic structure,which was a halogen free phosphorus nitrogen synergistic flame retardant:octahydro-2,7-di?N,N-dimethylamino?-1,6,3,8,2,7-dioxadiazadiphosphecine?ODDP?.The molecular structure of ODDP was characterized by ¹H-NMR spectroscopy,¹³C NMR spectroscopy,mass spectrum,elemental analysis and infrared spectroscopy.The thermal decomposition performance of ODDP was studied by TG.Four series of co-modified halogen-hree flame retardant waterborne polyurethane were deliberately designed and synthesized based on TDI,PPG,N,N-bis?2-hydroxyethyl?aminomethyl phosphonic acid diethyl ester?Fyrol-6?,ODDP,organophosphonate Exolit OP550 and DMPA.FTIR was utilized to characterize the molecular structures of co-modified flame retardant waterborne polyurethane and verified the chemical incorporation of the flame retardant monomer into the macromolecule of waterborne polyurethane.The properties of emulsion,such as size distributions,viscosity,stability,and the properties of film,such as water resistence,mechanical properties,fire resistance and thermal decomposition behavior,were characterized.The testing of flame retardancy shows that DPOWPUs has better flame retardancy.When the OP550 content reached 13 wt%,ODDP content reached 5 wt%,the limiting oxygen index increased to 31.4%,and UL-94 achieved a V-0 classification.The cone calorimetery results of materials were greatly improved,and the carbon yields of the DPOWPUs increased distinctly.Furthermore,the flame retardancy was further improved by physical blending DPOWPU and FOWPU,and the LOI can reach up to32.4%.TG and DSC tests show that the thermal decomposition behavior of the soft segment andhardsegmentco-modifiedhalogen-hreeflameretardantwaterborne polyurethane was significantly changed.With the increase of flame retardant,the decomposition temperatures of each degradation stage decreased,and the carbon residue of the polyurethane increased distinctly.With the incorporation of the soft segment and hard segment flame retardant,the phase separation degree of polyurethane was changed,which caused the water resistance and mechanical properties of the coating improved.The thermal decomposition and flame retardant mechanism of flame retardant waterborne polyurethane were studied by TG-IR,SEM and SEM–EDS.The infrared spectroscopy of the residues of DPOWPU and FOWPU showed the characteristic peaks of P-C?P=O and P-OH,which indicated that phosphorus residued in carbon layer.The results of SEM-EDS showed that the surface of char presented a continual and rugged structure,and the phosphorus content in the residues grew with the increase of phosphor-containing flame retardants.The results showed that the co-modified polymer DPOWPU and FOWPU performed condensed phase and gas phase synergistic flame-retarded mechanism.With the incorporation of the soft segment and hard segment phosphor-containing flame retardants,made phosphorus was more widely and evenly distributed in polyurethane macromolecular chain,which can accelerate the catalytic charring effect of phosphor-containing flame retardants,and promote NH₃ generation.The compact char layer can effectively inhibit oxygen transmission and heat diffusion during combustion,and NH₃ was nonflammable in oxygen.The thermal degradation kinetics of WPU?DPWPU15?FOWPU713?DPOWPU513and HDFWPU7 were studied by dynamic pyrolysis and calculated the reaction order,activation energy and preexponential factor?n,E andA?of each waterborne polyurethane.The application properties were evaluated by applying the DPWPU15?DPOWPU513?FOWPU713?HDFWPU7?HDFWPU4?HDFWPU3?HDFWPU2?HDFWPU1 in the textile of cotton and terylene.The results showed that the flame retardancy of the terylene treated by DPOWPU513?HDFWPU2?HDFWPU3?HDFWPU4?HDFWPU7 can pass the GB/T5455–1997 B1 standard,and the flame retardancy of the cotton treated by co-modified halogen-hree flame retardant waterborne polyurethane coatings was improved,too.Compared with TF–680,the co-modified halogen-hree flame retardant waterborne polyurethane coatings possess features of transparent,higher hydraulic pressure resistance,low loaded gum,low poison and low smoke during burning.