Preparation of microcapsules containing fine antimicrobial particles by sol-gel process in reverse suspension

当硫代磺化银配合物作为抗菌材料时，由于配合物在胶囊表面的偏析，不能得到分散型微胶囊。分散稳定剂的加入使微胶囊内的配合物含量有所提高。然而，当微胶囊悬浮在水中时，复合物的释放速度非常快。结果表明，它们不适合作为抗菌材料长期使用。因此，采用细AgCl颗粒代替硫代硫酸银络合物。非离子表面活性剂聚乙烯醇（PVA）作为分散稳定剂最有效，使AgCl在微胶囊中均匀分散。使用阴离子或阳离子表面活性剂均不能形成稳定的分散体。随着分散稳定剂浓度的增加，微胶囊中AgCl含量和AgCl释放到水中的量增加。释放率随分散稳定剂浓度的增加而降低，约为6%，持续48 h，微胶囊在普通处理过程中呈灰色。这是由于AgCl在紫外线照射下分解所致。通过与TTIP的二氧化钛杂交，微胶囊的颜色保持为白色。这表明二氧化钛可以有效地屏蔽紫外线照射和隐藏微胶囊的内部。在连续相中加入20 ~ 50 mol/m^3的TTIP可获得较好的复合材料。通过在微胶囊悬浮液中培养大肠杆菌，证实了微胶囊的抗菌作用。

When silver thiosulfato complex was used as antimicrobial material, dispersing-type microcapsule was not obtained because of the segregation of the complex onto the capsule surface. The complex content inside the microcapsule was somewhat improved by using dispersion stabilizer. However, the complex was released very fast, when the microcapsules were suspended in water. It was found that they were not suitable for the use as antimicrobial materials to be served for a long term.Thus, fine AgCl particles were used instead of silver thiosulfato complex. Polyvinylalcohol (PVA) of a nonionic surfactant was the most effective as a dispersion stabilizer, resulting in microcapsule in which AgCl was uniformly dispersed. The Use of anionic or cationic surfactant did not form stable dispersion. The AgCl content of the microcapsule and the amount of AgCl released to water increased with the increase in the dispersion stabilizer concentration. The release rate decreased with the dispersion stabilizer concentration to about 6% for 48 h.These microcapsules were changed to gray in color during the ordinary handling. This is due to decomposition of AgCl by UV irradiation. By hybridizing the microcapsules with titania from TTIP, they were kept white in color. This is suggested that titania is effective for shielding from UV irradiation and hiding the inside of the microcapsule. The addition of TTIP of 20 - 50 mol/m^3 to the continuous phase resulted in good composites.The antimicrobial effect of the microcapsule was confirmed by cultivating a colon bacillus (Escherichia coli) in suspension of the microcapsules.