Synthesis And Application Of Environmentally Friendly Flame Retardant Polyether Polyol

With the continuous development of society,rigid polyurethane foam has attracted more and more attention.However,its limiting oxygen index without flame retardant addition is about 18%,and its poor flame retardancy limit ssubstantially its practical applications and induce safety concern.The rigid polyurethane foam with flame retardants affected practically its mechanical properties and flame retardant durability.Therefore,the development of reactive flame retardant polyether polyols have been widely concerned in industries and academia.Firstly,a new environmentally-friendly melamine resin with low free formaldehyde content was synthesized with dialdehyde starch instead of formaldehyde solution and melamine as the raw materials.The effects of reaction parameters such as the mass ratio of melamine,dialdehyde starch and water,temperature,and time on product properties were investigated.The structure of the resin was characterized and identified by FT-IR.The viscosity of target products is below 2550m Pa·s,and the solid content is up to 43.0%.Those free formaldehyde are in the range of 0.062%?0.080%,and the adhesive strength is in the scope of1.40MPa?1.60MPa.Moreover,the storage period is 70?110 days.Secondly,an environmentally friendly melamine resin was used as the initiator and diethanolamine as the catalyst for ring opening polymerization with propylene oxide,and a reactive flame retardant polyether polyol with high nitrogen content was successfully synthesized.The effects of reaction parameters such as mass ratio of resin to propylene oxide,temperature and reaction time on the properties of product viscosity and hydroxyl value were studied.FT-IR and ~1H-NMR were used to characterize and identify the structure of the product.The viscosity of the target polyether polyol is 2000?2500m Pa·s,the water content is 0.20?0.30%,the hydroxyl number is 350?420mg KOH/g,and the acid number is 0.85?1.25mg KOH/g.Finally,the prepared flame retardant polyether polyols partially or completely replace polyether polyols 4110 which reacted with isocyanate to prepare flame retardant rigid polyurethane foam.The effect of the proportion of self-made polyols on the mechanical properties and flame retardancy of the foams were investigated.Its heat resistance and morphology were characterized by TG and SEM.The results showed that its compressive strength was above 350.0k Pa and the limiting oxygen index reached 30%.In conclusion,this environmentally friendly flame retardant polyether polyol provides a potential prospect for the development of PU flame retardant material and commercial applications.