Silicophosphate fireproof coatings for building materials

Abstract

The composition of silicophosphate fire-resistant coatings for wooden building structures was developed and their properties were investigated. Fireproof compositions were obtained by mixing aqueous solutions of liquid glass and acetic acid. As a phosphate-containing additive, phosphate buffer solutions were used, which were added to the silicic acid sol in different amounts and with different ratios of the components of the buffer pair. Adjusting the ratio of the components of the buffer solution led to a change in the pH of the buffer solutions, but adding them to the sol did not change its acidity, which was in the pH range of 5.5–6. The effect of the content and ratio of the components of the buffer pair on the change in the optical density of the obtained sols over time was studied. The highest durability of the flame retardant composition was recorded when using a buffer solution with a pH of 7 at a content of 20%. The embedding of phosphate ions into the siloxane framework of experimental gels has been chemically proven, which increases their fire resistance. It is shown that the amount of free phosphate anion in the intermicellar liquid of the experimental gels is less than 5%. The mechanism of the strengthening effect of the acetate buffer solution, which is formed during the mixing of the liquid glass solution with acetic acid, on the phosphate buffer solution is proposed. Fire-retardant compositions were applied to wood samples by the bath method and dried at temperatures of 80–100 ˚С in a drying cabinet. The fire protection effect of coatings was determined during fire tests in a ceramic pipe. The effect of the content of phosphate buffer solution on the fire-retardant properties of experimental coatings was studied. It is shown that increasing the content of the phosphate buffer solution reduces mass loss during fire tests, allows to increase the fire resistance of wood and transfer it to the group of "highly flammable".