| 摘要 |
PURPOSE:To facilitate handling and to improve dispersibility by adding and mixing a surfactant to a hydrated iron oxide pigment powder, subjecting this mixture to a compression and deaeration treatment and granulating this mixture so as to attain a grain size and porosity within a specified range. CONSTITUTION:The anion surfactant is added by 0.01-10wt.% per pigment powder weight to the hydrated iron oxide pigment powder having the long axis diameter within the range of 0.05-20mum and mixed with a high speed mixer, etc. The mixed and treated powder is subjected to the compression and degassing treatment under the condition adding the linear pressure within a range of 10-100000g/cm with a roll press, etc., then the treated matter is pulverized and classified by a conventional method to obtain a granulated matter having an average grain size within the range of 300-1500mu and porosity obtained by the formula within the range of 0.1-0.3. |
