| 摘要 |
PURPOSE:To obtain the titled filler effective for keeping opacity of paper after printing, having high yield in paper, by adding sulfuric acid to an aqueous solution of sodium silicate under specific conditions at two stages, neutralizing it. CONSTITUTION:>=30wt% sulfuric acid is added to an aqueous solution of sodium silicate having 6.5-10g/100cc concentration calculated as silica at room temperature -50 deg.C at once or continuously in a short time to make 40-75% neutralization degree, the solution is heated to 80-95 deg.C to form a flock of silica gel, which is aged at 80-95 deg.C for 60-150min. It is stirred at high speed to disperse the flock. The flock dispersion is heated to 90-100 deg.C, sulfuric acid having >=30wt% concentration is added to it at once or continuously in a short time, the dispersion is neutralized to 5-7pH, and it is stirred at high speed to disperse the flock of silica gel. |
