Intrinsic flame-retardant flexible polyurethane foam based on phosphorus-containing polyol with Si-O-C segment: Simultaneously improving fire safety and mechanical property

Phosphorus containing flame-retardants with low oxidation states are widely used in Flexible polyurethane foam (FPUF) due to their excellent gas-phase flame retardancy. However, achieving good migration resistance in prepared flame retardant while balancing or even improving the mechanical properties (such as ductility, good rebound ability) and flame retardancy of FPUF remains a challenging issue. To solve the above problem, we have designed diphenylphosphine oxide silicon glycol (DPPSG) that combines a phosphorus-based flame retardant group with a Si-O-C bond structure. Chemically linking DPPSG into the molecular chain of flexible polyurethane foam and mechanical properties at the same time. On one hand, DPPSG has good compatibility with polyether polyols 330, reacting uniformly with isocyanates and participating in the foaming and gelation process of FPUF. This ensures its enduring flame retardancy. On the other hand, the tensile strength and elongation at break of the flame retardant foam (10DPPSG foam) prepared by adding 10% DPPSG of polyether polyol 330 increased by 71.4% and 77.6% respectively. Moreover, even after 100 cycles of compression rebound testing, 10DPPSG foam exhibited excellent elasticity with a permanent compression deformation rate of only 4.9%. This work provides a new approach to develop FPUF that achieves a balance between mechanical and flame-retardant properties.