EFFECT OF SILICA-GEL CARRIERS ON THERMAL- STABILITY OF THE ANTIMICROBIAL MATERIAL WITH THIOSULFATO SILVER COMPLEX

Anti-microbial materials were prepared with thiosulfato-silver complex supported on silica gel. The materials were kneaded with resin, and t he color difference value Delta E(ab) of the surface against natural resin was measured. The Delta E(ab) values were improved with an incr ease of specific surface area, or a decrease of pore volume of silica gel carriers. Heat-treatment for silica gel carriers was useful for im provement of the suppression of Delta E(ab) values. It was suggested that the color changes of molded resins with anti-microbial materials were caused by oxidation after decomposition of the complexes with ads orbed water that was free from silica gel carriers by heat-treatment t hrough molding process. Heat-treatment for silica gel carriers decreas ed the adsorbed water on the carriers. Then this decrease resulted in reduction of free water from the carriers, and also resulted in inhibi tion for color changing of the resin.