SILICA GEL BEAD COATED WITH POLYMER COMPOSITION

摘要

PURPOSE:To enable the control of the dissipation speed of a liquid included in a gel by coating a silica gel bead with a polymer composition containing a water-insoluble alginic acid salt. CONSTITUTION:A silica sol having a pH of 8.0-8.5 and produced by mixing water glass with a mineral acid is ejected from a nozzle into air and the droplets are thrown into water and washed with water to obtain spherical silica beads 1 having particle diameter of 1-5 mm. The beads 1 are immersed in an aqueous solution of a water-soluble alginic acid salt or its mixture with a water-soluble polymer (e.g. PVA) to form a coating film of the polymer composition on the surface of the bead. The coating film is cured by throwing the beads into an aqueous solution of a water-soluble alkaline-earth metal salt to obtain a bead 1 coated with a polymer composition 2 containing a water- insoluble alginic acid salt. The bead 1 is thrown into an amphiphatic liquid (e.g. methanol) and left standing for 1-48 hr to substitute the water in the bead with the amphiphatic liquid.