PROBLEM TO BE SOLVED: To provide a hollow granule produced by coagulation of particulate matter with a novel shape control method which has been conventionally impracticable.SOLUTION: A hollow granule is produced by coagulation of particulate matter of a metal oxide with a particle size of less than 0.1 μm. The hollow granule is obtained as follows. A mixed liquid including the particulate matter, which is composed of particulate titanium oxide surface-treated with silicic acid anhydride and of which the surface is positively or negatively charged, is produced by dispersing the particulate matter in a dispersion medium selected from aqueous solvents and alcohol- or ether-type solvents. The particulate matter is dispersed in the mixed liquid in such a way that an average surface-to-surface distance of the particulate matter in the mixed liquid satisfies inequality LDLVO≥LWoodcock. The mixed liquid is turned into liquid droplets with a size of less than 100 μm, and the dispersion medium is evaporated from the liquid droplets and the hollow granule is obtained by drying.COPYRIGHT: (C)2014,JPO&INPIT【課題】現状では不可能であった新規な形態制御法による粒状物質が凝集してなる中空顆粒を提供する。【解決手段】粒子径0.1μm未満の金属酸化物の粒状物質が凝集してなる中空顆粒である。この中空顆粒は、次のようにして得られるものである。無水ケイ酸で表面処理された微粒子酸化チタンからなると共に表面が正電荷又は負電荷を帯びた粒状物質を、水系溶媒、アルコールないしエーテル系溶媒より選ばれる分散媒体中に分散し、上記粒状物質を含む混合液体を製造する。上記混合液体中の粒状物質の平均表面間距離が「LDLVO≧LWoodcock」となるように上記混合液体中の上記粒状物質を分散させる。上記混合液体を100μm未満の液滴とし、該液滴から上記分散媒体を蒸発させて乾燥させる。【選択図】図4
