Construction Of Novel Phosphorus Nitrogen Boron Synergistic Flame Retardant And Its Application In Flexible Polyurethane Foam

Flexible polyurethane foam（FPUF）is widely used in upholstered furniture,automotive interiors and other fields due to its light weight,low density,high resilience,and breathability.However,the problems of FPUF,such as flammability,severe molten droplets,and high smoke toxicity,have caused great hidden dangers to its use safety.However,traditional flame-retardant phosphorus-based flame retardants have a certain negative impact on the natural environment.Therefore,it is of great significance to find an environmentally friendly alternative flame retardant.Based on the combustion characteristics of FPUF and different flame retardant mechanisms,the flame retardancy,smoke suppression,and anti droplet modification of FPUF are successfully a CSeved through three strategies:improving the weight gain and flame retardancy efficiency of phosphorus containing flame retardants,preparing low phosphorus content flame retardants,and constructing a halogen-free and phosphorus-free efficient flame retardant system.The corresponding flame retardancy mechanisms are also explored.On this basis,the multifunctional modification of soft foam materials such as antibacterial and hydrophobic has been realized.Details as follows:1.Based on the supramolecular reaction,a low-cost DTPMP-DCD novel phosphorus-nitrogen flame retardant system is constructed and applied to FPUF.The experimental results show that:the weight gain is less than 30%,the horizontal combustion level of the FPUF/DTPMP-4DCD sample reaches the HF-1 level,the limiting oxygen index（LOI）reaches 28.4,the peak heat release rate（p HRR）,the total heat release（THR）and the peak smoke release rate（p SPR）decreased by58.2%、44.1%and 16.7%,respectively,compared with pure FPUF.The flame retardant mechanism analysis show that the reaction product of DTPMP and DCD contributed to the formation of dense,stable and defect-free char layers.The introduction of the flame retardant system protects the tensile strength of the composite system,and the comfort factor increases from 1.61 of pure FPUF to 3.12,endowing the foam system with excellent support.2.Replace DTPMP with phytic acid,and rely on the coordination between Zn²⁺and natural polyphenols,and use AP/PA/Zn system.Based on the flame retardant modification of FPUF,the flame retardant modification and multifunctionalization of FPUF with low phosphorus content have been realized.When the weight gain is 42.6%,the horizontal combustion of the FPUF/AP/3PA/Zn sample reaches the HF-1level,the LOI reached 24.2,and the p HRR,THR and p SPR decreased by51.0%,37.5%and 16.6%,respectively,compared with pure FPUF.Microstructural analysis reveals that the synergistic effect of AP/Zn and PA contribute to the formation of a char layer with higher density and fewer defects.In addition,the introduction of Zn²⁺endowes the foam system with excellent antibacterial properties against Escheri CSa coli and Staphylococcus aureus.3.Design a CS-SPB bio-based phosphorus-free and halogen-free high-efficiency flame-retardant coating for the FPUF through layer-by-layer self-assembly,and the flame-retardant system is impregnated into the FPUF.When the weight gain was only 25.6%,FPUF/CS-SPB reaches the level of horizontal combustion HF-1,and the LOI increases to 30.2,making the modified sample belongs to flame retardant materials.Its p HRR,THR and TSP are respectively reduced by68.5%,24.0%and 61.4%,and the high-temperature residual rate increases by 195.1%.The compound system can promote the matrix to form a denser and higher-strength char layer,and exert the effect of condensed phase flame retardancy.FPUF is endowes with excellent hydrophobicity without affecting the flame retardant performance by painting a small amount of PDMS,and the water contact angle is increased from 76.8°to 130.1°.