Study of the influence of sodium hexametaphosphate on the properties of silica-containing fireproofing coating for building materials

Lysak Nataliia

National University of Civil Protection of Ukraine

https://orcid.org/0000-0001-5338-4704

Skorodumova Olga

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-8962-0155

Chernukha Anton

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-0365-3205

Goncharenko Yana

National University of Civil Protection e of Ukraine

https://orcid.org/0000-0002-1766-3244

Melezhyk Roman

National University of Civil Protection of Ukraine

http://orcid.org/0000-0001-6425-4147

DOI: https://doi.org/10.52363/2524-0226-2025-41-9

Keywords: fire-retardant silica-containing coatings, sodium hexametaphosphate, building materials, heat resistance, fire resistance, wood, polystyrene foam

Аnnotation

The composition of a silicophosphate composition intended for fire protection of building materials was developed. Solutions of liquid glass, acetic acid and sodium hexametaphosphate were used as starting components. The influence of the content of the phosphorus-containing additive on the rheological properties of silicic acid sols was studied. By spectrophotometry, it was established that the latent coagulation time in the entire range of the studied content of sodium hexametaphosphate is ~20 minutes. The highest values of optical density were recorded for a sol with an additive content of 0.3 %. The probability of the influence of electrostatic and steric effects, which depend on the concentration of the phosphorus-containing additive, on the stability of the sol was considered. It is assumed that the minimum value of sol survivability at 0.3 % of the additive is associated with a decrease in the ζ-potential and compression of the double electric layer. The results of infrared spectroscopy confirmed the hypothesis of two different mechanisms of polycondensation in different intervals of hexametaphosphate content. At a content below 0.3 %, a linear mechanism of polycondensation was noted, above 0.3 % – a reticular one. Fire tests were carried out on samples of wood and extruded polystyrene foam coated with compositions of the studied composition. The best fire-retardant properties were recorded for systems with a sodium hexametaphosphate content of 0.1–0.3 %. Processing of wood samples allowed transferring the material to the “hard-to-flame” group, the mass losses of the samples were less than 10 %. Samples of extruded polystyrene foam did not support combustion at an additive content of 0.1 % or did not burn at all at a content of 0.3%, mass losses were less than 3 %. The effect of the number of coating layers on the effectiveness of its fire-retardant action was assessed: for wood in the range of hexametaphosphate concentrations of 0.1-0.3 %, three-layer coatings were the most heat-resistant, for extruded polystyrene foam at a content of 0.3 % – one- and two-layer.

References

1. Hou, X., Guo, L., Wang, F. (2021). Inhibiting effects of three phosphates on coal spontaneous combustion. International Journal of Coal Preparation and Utilization, 42(10), 3054–3069. doi: 10.1080/19392699.2021.1932844
2. Zhu, Z., Rao, W., Kang, A., Liao, W., Wang, Y. (2018). Highly effective flame retarded polystyrene by synergistic effects between expandable graphite and aluminum hypophosphite. Polymer Degradation and Stability, 154, 1–9. doi: 10.1016/j.polymdegradstab.2018.05.015
3. Ji, W., Yao, Y., Guo, J., Fei, B., Gu, X., Li, H., Sun, J., Zhang, S. (2020). Toward an understanding of how red phosphorus and expandable graphite enhance the fire resistance of expandable polystyrene foams. Journal of Applied Polymer Sci-ence, 137(35). doi: 10.1002/app.49045
4. Liu, J., Guo, Y., Chang, H., Li, H., Xu, A., Pan, B. (2018). Interaction between magnesium hydroxide and microencapsulated red phosphorus in flame‐retarded high‐impact polystyrene composite. Fire and Materials, 42(8), 958–966. doi: 10.1002/fam.2650
5. Baby, A., Tretsiakova-McNally, S., Arun, M., Joseph, P., Zhang, J. (2020). Re-active and Additive Modifications of Styrenic Polymers with Phosphorus-Containing Compounds and Their Effects on Fire Retardance. Molecules, 25(17), 3779. doi: 10.3390/molecules25173779
6. Zhu, Z., Xu, Y., Liao, W., Xu, S., Wang, Y. (2017). Highly Flame Retardant Expanded Polystyrene Foams from Phosphorus–Nitrogen–Silicon Synergistic Adhe-sives. Industrial & Engineering Chemistry Research, 56(16), 4649–4658. doi: 10.1021/acs.iecr.6b05065
7. Lysak, N., Skorodumova, O., Chernukha, A. (2023). Development of a fire-proof coating containing silica for polystyrene. Problems of Emergency Situations, 2(38), 192–202. doi: 10.52363/2524-0226-2023-38-10
8. Lysak, N., Skorodumova, O., Chernukha, A., Goncharenko, Y., Melezhyk, R. (2024). Silicophosphate fireproof coatings for building materials. Problems of Emer-gency Situations, 1(39), 262–271. doi: 10.52363/2524-0226-2024-39-19
9. Li, Y., Guo, A., Xu, X., Xue, Y., Yan, L., Hou, F., Liu, J. (2022). Preparation and properties of highly elastic, lightweight, and thermally insulating SiO2 fibrous porous materials. Materials, 15(9), 3069. doi: 10.3390/ma15093069
10. Zhang, Y., Liu, H., Liu, J., Tong, R. (2019). Effect of sodium hexametaphosphate and trisodium phosphate on dispersion of polycarboxylate superplasticizer. Materials, 12(24), 4190. doi: 10.3390/ma12244190
11. Ramirez, A., Rojas, A., Gutierrez, L., Laskowski, J. S. (2018). Sodium hexametaphosphate and sodium silicate as dispersants to reduce the negative effect of kaolinite on the flotation of chalcopyrite in seawater. Minerals Engineering, 125, 10–14. doi: 10.1016/j.mineng.2018.05.008
12. DSTU 4479:2005. Rechovyny vohnezakhysni vodorozchynni dlia derevyny. Zahalni tekhnichni vymohy ta metody vyprobuvannia. Chynnyi z 01.10.2006. Кyiv: Derzhspozhyvstandart Ukrainy, 17.
13. DSTU 8829:2019. Pozhezhovybukhonebezpechnist rechovyn i materialiv. Nomenklatura pokaznykiv i metody yikhnoho vyznachennia. Klasyfikatsiia. Chynnyi z 01.01.2020. Vyd. ofits. Kyiv: UkrNDNTs, 75.
14. Lysak, N., Skorodumova, O., Chernukha, A., Kochubei, V., Sotiriadis, K. (2025). Study of Gelation Processes in Flame Retardant Compositions of the SiO2 Sol System – A Phosphate-Containing Additive. Defects and Diffusion Forum, 438, 101–110. doi: 10.4028/p-I2sYIR
15. Zribi, M., Baklouti, S. (2021). Investigation of phosphate based geopolymers formation mechanism. Journal of Non-Crystalline Solids, 562, 120777. doi: 10.1016/j.jnoncrysol.2021.120777
16. Karan, R., Pal, P., Maiti, P., Das, K. (2021). Structure, properties and in-vitro response of SiO2-Na2O-CaO-P2O5 system, based glass-ceramics after partial replace-ment of Na2O by Li2O. Journal of Non-Crystalline Solids, 556, 120554. doi: 10.1016/j.jnoncrysol.2020.120554