PROBLEM TO BE SOLVED: To provide an aqueous dispersion prepared by dispersing a hardly water-soluble active component having bactericidal or bacteriostatic activity by incorporating it in nano-sized fine particles as an O/W type, also expressing the bactericidal or bacteriostatic activity and maintaining preservation stability.SOLUTION: This aqueous dispersion is prepared by dispersing liquid or solid particles containing (A) a hardly water-soluble actively acting substance and (B) a lipophilic matrix and having &le200 nm mean particle diameter in water. The content of (A) the hardly water-soluble actively acting substance is 0.01 to 20 mass% based on the total liquid mass, also the content of (B) the lipophilic matrix is 0.2 to 20 mass% based on the total liquid mass and the contained mass of (A) the hardly water-soluble actively acting substance is &ge0.05 fold of the contained mass of (B) the lipophilic matrix. The aqueous dispersion contains (C) an anionic surfactant or (D) a cationic surfactant of 0.001 to 0.2 fold of the contained mass of the particles.COPYRIGHT: (C)2009,JPO&INPIT【課題】殺菌・静菌能を有する難水溶性活性成分をナノサイズの微粒子に含ませてO/W型に分散させ、しかも、殺菌・静菌能を発現させると共に、保存安定性をも維持させる。【解決手段】水分散液は、殺菌・静菌能を有する難水溶性活性作用物質(A)及び親油性マトリクス(B)を含む平均粒子径が200nm以下の液体又は固体の粒子が水に分散したものである。難水溶性活性作用物質(A)の含有量が液全体質量の0.01~20質量%であると共に、親油性マトリクス(B)の含有量が液全体質量の0.2~20質量%であり、且つ難水溶性活性作用物質(A)の含有質量が親油性マトリクス(B)の含有質量の0.05倍以上である。水分散液は、粒子の含有質量の0.001~0.2倍のアニオン界面活性剤(C)又はカチオン界面活性剤(D)を含む。【選択図】なし
