Inorganic transparent intumescent interlayer coatings for fire rated glass

Abstract

An inorganic alkali silicate based fire-resistant coating has been developed for laminated glass to slow the spread of heat in the case of a fire breakout by the mechanism of intumescing. Various formulations of the interlayer coating were synthesized with different SiO2 : M2O molar ratios using colloidal silica solution with the addition of an alkali silicate. The incorporation of silica particles was found to improve the water stability of hygroscopic silicate-based coatings that are commonly used commercially.

This study investigates the stability of the fire-resistant coatings by subjecting their bulk forms to high and low humidity conditions. The effect of silicate on the transparency of the coatings were then explored using X-ray Diffraction (XRD) analysis. The study also assesses the fire performance of the coating based on its SiO2 : M2O molar ratio, colloidal silica particle size, and the type of metal alkali cation used. Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), intumescent and ISO 834 furnace tests, and XRD analysis were employed to characterize the coatings so as to identify the key factors affecting contributing to their performance.

The lab synthesized fire rated coatings were found to exhibit superb stability in terms of retaining its form and transparency after exposure to high and low humidity conditions. Thermal analysis showed that a larger SiO2 : M2O molar ratio corresponds to higher dehydration temperatures and lower enthalpies while intumescent tests revealed that such samples demonstrated lower degrees but more stable intumescent materials. Finally, XRD analysis proved that the addition of silicate does in fact plays a role on the transparency of the sample by improving the dispersity of the colloidal silica particles and facilitating their separation to prevent agglomeration. It also provides insights on the intumescence structure of the material at various temperatures. It was demonstrated that the stability of the intumescent material, as well as the thermal properties of the fire-resistant coating are key factors for superior fire performance.