Electrostatic self-assembly endows cellulose paper with durable efficient flame retardancy and mechanical performance improvement.

Flameproof modification of paper can improve safety and application performance. However, traditional paper is prone to moisture absorption, resulting in significant reduction in flame retardant performance, even complete failure, greatly limiting the application environment. In order to achieve long-term flame retardant properties of paper, while avoiding the loss of physical properties caused by the introduction of flame retardants, in this work, a plant acid/phosphate and melamine formaldehyde coating (PyA/PA-MF) is prepared through electrostatic self-assembly for durable flame retardant performance of cellulose paper. Due to the electrostatic interaction, the paper surface become greatly rough with introduction of PyA/PA-MF, a uniform microsphere structure is formed on the surface of the paper cellulose, which effectively fix the phosphorus-containing groups. The oxygen index reaches 33 % and the carbon length was only 6.3 ± 0.2 cm, the pHRR and THR are decreased by 80 % and 73 %, respectively. After being immersed for 72 h, the oxygen index is still 31.4 % and carbon length is no more than 12 cm. mechanical property of modified paper is significant increased in the tensile strength (2.4 MPa) compared to the blank paper (1 MPa), as well as that the whiteness of the surface of the modified paper will not change. In summary, PyA/PA-MF endows paper long-term flame retardant performance while maintaining its basic performance.