Improving the Fire-Retardant Properties of Cotton-Containing Textile Materials Through the Use of Organo-Inorganic SiO₂ Sols

Abstract

The effect of fire-retardant compositions based on organo-inorganic SiO2 sols without the use of flame retardants on increasing the fire resistance of cotton-containing textile materials has been studied. Previous studies have shown that the combined use of silicate coatings and flame retardants of simple structure prevents the ignition of impregnated samples of cotton-containing fabric and the proposed chemistry of this process. These studies did not use flame retardants to obtain more information on the effect of the composition and concentration of experimental organo-inorganic SiO2 sols on the fire resistance of treated tissues. The compositions were prepared by the sol-gel method using a technical product – liquid glass – with a silicate modulus of 2,5 and acetic acid solution. The influence of sols concentration in terms of conditioned SiO2 on their rheological features has been studied. It was found that the optical density, fluidity and survivability of experimental sols depend on the concentration of SiO2 in the sol. The compositions were applied to the fabric by the bath method in layers: each layer of the coating was fixed on the surface of the fabric by thermal shock in an oven at temperatures of 80-100 °C. Untreated cotton fabric caught fire under the influence of fire after 7 seconds. Impregnated tissue samples did not ignite under the action of fire, but gradually charred. To determine the effect of coating thickness and SiO2 concentration in the sol on the fire resistance of impregnated fabric samples, fire tests at a gas pressure of 0,2 MPa were performed for 8 s and the area of damage to the reverse side of the fabric was determined. Prolonged exposure to the flame resulted in a crack in the center of the charred spot. In the absence of flame retardants in the fire-retardant composition after removal of the fire source, decay was observed. The time for which a crack is formed in the sample under the action of fire was determined at the time of onset of tissue destruction. It is shown that in the case of using a sol of 10% concentration it is necessary to apply three layers of coating, which doubles the fire resistance (from 7 s for untreated fabric to 15 s for impregnated fabric), the start time of destruction increases 5 times (from 1 min to 5,5 min). The area of damage to the reverse side of the fabric not treated and impregnated with the experimental coating is reduced from 632 mm2 to 0, respectively.