Silicophosphate fireproof coatings for building finishing materials

The composition of silicophosphate composition based on liquid glass for fire protection of building finishing materials has been developed. The compositions were prepared by mixing aqueous solutions of liquid glass and acetic acid with the addition of phosphate buffer solutions with a pH of 6–8. The phase composition of the experimental compositions was investigated by infrared spectroscopy and the formation of Si–O–P bonds was established, which indicates the incorporation of phosphate ions into the siloxane framework of polysilicic acid gels. It was established that the polycondensation mechanism is influenced by the pH value of the phosphate buffer solution, as well as its content. The use of a buffer solution with a pH of 6 leads to the initialization of mainly net polycondensation in liquid glass sols. Increasing the pH to 7–8 ensures linear polycondensation of polysilicic acid, which increases the homogeneity of the gel coating, provides elasticity, and increases its fire-retardant effect. Conducted fire tests showed that the best fire-resistant properties have systems with a buffer solution content of 20–25 % with a pH of 7, which provide maximum resistance to fire and minimal loss of mass of samples during exposure to high temperatures. For such compositions, the 1st group of flame retardant efficiency is established, and the treatment of wood samples with them allows the material to be transferred to the "high-flammability" group. Extruded polystyrene samples covered with the developed compositions do not burn, the absence of burning drops is noted. The obtained results emphasize the prospects for the further development of such systems for the protection of building materials.