TECHNOLOGICAL FEATURES OF OBTAINING COMPLEX SILICA SOLS FOR FIRE PROTECTION OF BUILDING FINISHING MATERIALS

Abstract

The influence of the technology for obtaining fire-retardant compositions based on liquid glass for fire protection of building finishing materials was studied. The influence of the silicate module of liquid glass on the rheological properties of silicic acid sols modified with phosphate-containing com- pounds was studied. According to the results of spectrophotometric measurements, it was established that the ratio n(SiO₂)/n(Na₂O) in liquid glass within 2.5–3 does not significantly affect the survivability of the compositions. The influence of the ratio of the initial components on the duration of solidification of the sols was determined. It was established that the preliminary introduction of 0.1 wt. % Trilon B into tap water allows obtaining stable silicic acid sols over time, which is a prerequisite for the for- mation of a homogeneous fire-retardant coating. Fire tests were carried out on samples of wood and extruded polystyrene foam coated with compositions of the studied composition. It was found that the content of 2 % orthophosphoric acid and 0.1 % sodium hexametaphosphate provides mass loss of wood samples less than 7.5 %, which corresponds to the I group of fire-retardant efficiency of coatings, and the protected material belongs to the group of low-flammability. For extruded polystyrene foam, the best fire-retardant effect was demonstrated by compositions with a sodium hexametaphosphate content of 1 %: mass loss of samples varied within 1–3 %, burning drops were not formed, and the samples did not support combustion. It is assumed that the increased fire resistance of coatings with a higher content of phosphorus-containing additive is associated with the fusibility of sodium compounds and their abil- ity to transfer the fire-retardant coating to a visco-plastic state, which contributes to the dissipation of deformation stresses and prevents the formation of cracks in the coating. Keywords: fire-retardant silica-containing coatings, silicophosphate coatings, modifying phosphorus- containing additives, building materials, heat resistance, fire resistance, extruded polystyrene foam