| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite material of calcium carbonate and silica having high oil absorption characteristics and giving a paper high effect for bulkiness when used as a filler, increasing printing suitability. SOLUTION: The composite of calcium carbonate and silica having oil absorption amount of 170-280 ml/100g, which has been difficult to be produced conventionally, can be produced by the steps of: (1) obtaining a slurry containing calcium silicate by mixing and reacting an aqueous alkali silicate metal salt solution to an aqueous slurry, containing calcium chloride and calcium sulfate in the mole ratio of 10:90-75:25 and the Ca concentration of 1.0-6.0 g/100 ml on the basis of CaO, to give CaO/A<SB>2</SB>O (A represents an alkali metal) in the range of a molar ratio of 0.8-1.2 and a pH of at least 9; and (2) contacting the slurry with carbon dioxide of the amount making the pH of the slurry at most 6.5. COPYRIGHT: (C)2010,JPO&INPIT |
