| 摘要 |
PURPOSE:To obtain a barium sulfate filler which itself has excellent whiteness or transparency, can be colored with a colorant with any desired hue, has conductivity stable against changes in both temperature and humidity, and is highly dispersible in a resin or the like. CONSTITUTION:The filler consists of a particulate core of barium sulfate and a coating film of tin oxide doped with niobium or tantalum. The core has a specific surface area of 0.1-150m<2>/g in an uncoated state, and the film contains 0.1-10wt.% (in terms of Nb or Ta based on tin oxide) niobium or tantalum and has a thickness of 2-80nm. The production process of the filler comprises combining a slurry containing barium sulfate particles with a solution containing a tetravalent tin compound to prepare a combined solution of a pH of 11-14, adding an acid solution of a pentavalent niobium compound or tantalum compound in an amount to give 0.1-10wt.%, based on the weight of the tin oxide, Nb or Ta atoms to the combined solution, adjusting the pH of the resulting solution to 1-5, separating the formed precipitate from the solution, drying the separated precipitate, and firing it in an inert atmosphere or a reducing atmosphere. |
