| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ultraviolet absorber reduced in the tendency toward agglomeration and having improved transparency, dispersibility, and the effect of intercepting ultraviolet rays in region A by coating the surface of a flaky substrate with zinc oxide ultramicroparticles. SOLUTION: At least 0.005 mol, per mol of the zinc salt, of a complexing agent is added to an aqueous suspension containing 100 pts.wt. flaky substrate having a mean particle diameter of 0.5-10.0 μm, and the resulting mixture is heated to 60 deg.C or above. A zinc salt solution and an alkali carbonate are added to the aqueous suspension at a pH of 8 or above, and an alkaline solution is added to adjust the mixture to a pH of 8 or above and to coat the surface of the flaky substrate with the basic zinc carbonate ultramicroparticles. The coated microparticles are then filtered, washed, and fired at 300-900 deg.C, desirably, 500-900 deg.C to coat the surface of 100 pts.wt. flaky substrate with 30-250 pts.wt., desirably, 50-150 pts.wt., more desirably, 70-130 pts.wt. zinc oxide microparticles having a mean particle diameter of 100 nm or lower. |
