| abstract |
Prodn. of sol-gel particles (I) contg. SiO2, which are resistant to breaking, involves combining an aq. alkali metal silicate soln. (II) with an aq. acid soln. (III), converting the resultant hydrosol into hydrogel particles (IV) in a water-immiscible liquid or in air and subjecting (IV) to further sol-gel process treatment stages. The novelty is that highly disperse filler (V) is added to (II) and/or (III). (I) contg. 1-85 (wt.)% (V) (w.r.t. total solids) are also claimed. (V) pref. has a particle size of 1-50, esp. 1-20 nm and is an inorg. cpd., i.e. aluminosilicate, Al2O3, TiO2 or esp. SiO2. (I) have a SiO2 matrix, contain 1-85, pref. 25-80% (V) and are spherical. |