| 摘要 |
PURPOSE:To improve the effect of metal compd. in a bead, to reduce scattering and reflection of light, and to improve deodoring effect by specifying the particle size and content of metal compd. particles in the bead so as to prevent formation of voids of specified size or larger in the bead. CONSTITUTION:A water-in-oil emulsion is prepared by emulsifying an aq. soln. of alkali metal silicate having a dispersion of metal compd. fine particles in the presence of an emulsifier. Then, this emulsion is mixed with an aq. soln. of compd. which gives the reaction of forming insoluble silica for an alkali metal silicate, so as to produce silica beads containing the metal compd. In this process, it is specified that the primary particle size of the metal compd. fine particles is 0.001-0.3mum, the SiO2 content in the alkali metal silicate soln. is >5.0mol/l and that the amt. of metal compd. in the obtd. silica beads is 0.1-30wt.%. Thereby, the silica beads of this invention contains no void larger than >=0.3mum in size. |
