| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide retroreflective glass beads and heat treatment thereof to improve the Y-value (brightness) in the three-color system although the beads contain an iron content as an impurity. SOLUTION: Glass beads consist of glass containing TiO2 and BaO in total >=60% and 0.005 to 0.1 mass% Fe2O3 as a coloring impurity, and the beads have 1.8 to 2.1 refractive index. By heat treating the glass at 300 to 650 deg.C, Fe is produced in the glass and the produced Fe is bonded in the mesh structure of barium titanium oxide in the glass to color the glass into light brown to light yellow. Thus, the Y value (brightness) in the three-color system is controlled to >=50 and <=75.</p> |
