METHOD OF PRODUCING MICROSPHERES FOR RETROREFLECTIVE COATINGS Russian patent published in 2019 - IPC C03B19/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing glass microspheres, which can be used in road surface marking and in production of retroreflective devices. Sodium-calcium-silicate glass is produced in a gas or electrical glass-melting furnace according to conventional technology in glass making, followed by granulation of molten glass. Produced glass granulate is further subjected to grinding and classification of glass powders obtained by grinding into fractions in range of 5–1500 mcm. Glass microspheres are then formed from the obtained glass powders in a suspended state in the ascending gas flow at temperature of 1100–1500 °C. Cooling of glass mass containing 54.0–70.0 wt. % SiO₂, 17.0–30.0 wt. % CaO, 7.0–16.0 wt. % Na₂O and/or K₂O, 0–5.0 wt. % MgO, 0–5.0 wt. % Al₂O₃ and not more than 0.1 wt. % Fe₂O₃, is carried out at a rate preventing crystalline phase formation.

EFFECT: technical result consists in improvement of efficiency of optical refraction of glass microspheres by increasing the refraction index of glass, increasing the coefficient of optical transmission of glass, increasing surface tension of glass and reducing the temperature range of variation of viscosity of glass in range of 10⁴ Pa*s to 10⁸ Pa*s.

4 cl, 2 tbl, 4 ex