Study of water resistance of silica protective coatings based on liquid glass

Abstract

The water resistance of cotton textile materials impregnated with SiO2 sols obtained on the basis of liquid glass was studied. Experimental coatings on fabrics were prepared by the bath method. After applying each coating layer and removing excess ash, the experimental samples were dried at (60–80) ºС. Fabric samples impregnated with sol SiO2 were immersed in containers with distilled water maintaining the same sample/water ratio. The fire-retardant properties of the coatings were determined after standing in water for 2–72 hours. The degree of destruction of coatings during hydrolysis was studied by determining the optical density of the hydrolyzate above the surface of the samples using the spectrophotometric (KFK-2) method. Fire-resistant properties were determined at a laboratory installation for fire tests. Under the influence of water, partial hydration of the surface of the silica coating occurs, which does not lead to its destruction. The presence of a layer of adsorbed water molecules on the surface of the coating is the reason for an additional increase in the fire-retardant properties of the samples. It is shown that the degree of homogeneity of the SiO2 sol affects the resistance to hydrolysis of the gel coatings. Low-concentration SiO2 sols (8 %), which are characterized by high fluidity and have a long service life, have a predominant effect. The long-term effect of water provides an increase in the fire-retardant properties of impregnated samples in comparison with non-impregnated fabric samples. The concentration and degree of homogeneity of the SiO2 sol have a predominant effect on the flame retardant properties. The surface layer of flame-retardants prevents the final burning and smoldering of the samples after removing the fire source, but does not significantly affect values of flame-retardant properties.